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IMAGING OF BREAST MASSES
BREAST IMAGING
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IMAGING OF BREAST MASSES Lawrence W. Bassett, MD
Standardized terminology has been developed for the description of masses depicted on mammography and similar systems are under development for breast ultrasonography and breast MR imaging. The use of standardized terminology improves the communication of findings and management recommendations. It also facilitates assessment of the effectiveness of screening through medical audits. For this reason, the standardized terminology of the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS)' has been incorporated into this article on breast masses. The article places an emphasis on the evidence-based approach to the appropriate evaluation and management of breast masses, sometimes referred to as appropriateness guidelines.' The evidence-based approach relies on peer-reviewed published research in scientific journals rather than traditional approaches or the anecdotal experiences of individual practitioners.26The ability to compare and combine the results of published clinical research studies is essential to the development of evidence-based appropriateness guidelines. The use of standardized terminology in the radiology literature also facilitates the development of these guidelines. When published research studies do not address a specific clinical situation, appropriateness guidelines are based on a consensus of a panel of expert^.^' In addition to the use of the most effective imaging technology, appropriateness guidelines
should meet cost-effectiveness criteria. There should be a reasonable likelihood that the information obtained from additional workup will affect management decisions and that the proposed work-up is the least expensive 39 method to get the essential inf~rmation.'~, Because other articles in this issue address novel technologies, the focus of this article is on mammography and sonography for the evaluation of breast masses. The organization of the article also reflects some differences in the management of nonpalpable masses, palpable masses in women over the age of 30, and palpable masses in women under the age of 30. STANDARDIZED DESCRIPTION OF MAMMOGRAPHIC FEATURES
In the ACR BI-RADS,' a mass is defined as a space-occupying lesion seen in at least two projections. If seen in only one projection, a suspected mass is called a density. The mass could be obscured by breast tissues on other views or it could represent a pseudomass created by superimposition of tissues (Fig. 1). Further work-up determines the real nature of the finding. In standardized terminology, the mammographic features of a verified mass include its shape, margins, density, size, location, and any associated features. The shape of a mass can be described as round, oval, lobular, or
From the Department of Radiological Sciences, University of California Los Angeles School of Medicine, Los Angeles, California
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Figure 1. Density due to superimposed normal tissues. A, Mediolateral oblique view shows a possible irregular, spiculated mass (arrow) in the upper breast. B, Craniocaudal view does not confirm the presence of a mass. C,Ninety-degree lateral view shows no mass. 0,Spot compression of upper breast in mediolateral oblique projection indicates that the density represents a superimposition of normal tissues.
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Figure 2. Terminology used to describe the shape of a mass.
irregular (Fig. 2). The margins of a mass, generally recognized as the most reliable feature in determining the likelihood of malignancy,17 can be described as circumscribed; microlobulated; obscured; ill-defined (indistinct); or
spiculated (Fig. 3). When the margins are not uniform throughout, the descriptor indicating the portion of greatest concern should generally be used.l* If the mass is mostly circumscribed but not completely visualized because
Figure 3. Terminology used to describe the margins of a mass.
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of adjacent tissue of similar density, the term obscured is applied. The density or radiographic attenuation of the mass relative to an equal volume of normal fibroglandular tissue is often included in the description. Appropriate terms are highdensity; equal density (isodense);low density; or fat-containing (radiolucent). Although carcinomas are usually of high density, some are isodense or low in density. This feature is not always reliable. On the other hand, fat within the actual confines of a mass is a reliable sign of benignity (Fig. 4). Other findings that are useful in identifying the nature of a mass include associated findings, such as calcifications (Fig. 5), skin retraction, skin thickening, and ipsilateral lymph node enlargement. As a general rule, the most ominous of the features should be used to determine the final description and assessment of the rnass.I* In the evaluation of masses, the final assessment is often determined by a combination of the mammographic, ultrasonographic, and clinical findings.
Figure 5. Typical coarse, rim calcification identifies this mass as a benign fibroadenoma.
NONPALPABLE MASSES Nonpalpable masses are usually identified as a result of screening mammography or as an incidental finding on a diagnostic examination. Figure 6 provides a suggested algorithm for the work-up of a nonpalpable mass. The pathways in the work-up protocol should be evidence-based whenever possible. Of course, the algorithm may need to be adjusted for individual patients and their clinical histories. Density: Mass Versus Pseudomass or Summation Shadows
Figure 4. Fat-containing mass. The patient felt a subareolar mass. Craniocaudal mammogram reveals a mass (arrows) containing fat and fibroglandular tissue density elements. The findings are pathognomonic for lipofibroadenoma, a benign mass requiring no further workup.
As illustrated in Figure 1, if a suspected mass is seen on the mediolateral oblique or craniocaudal view but cannot be confirmed on the other standard projection, it is usually referred to as a density. Additional imaging should be performed to confirm that a mass is truly present. The additional imaging may include a 90-degree lateral view; spot compression; roll views (e.g., the breast is rolled medially .or laterally for the craniocaudal view); and tangential views.7,14, 32 If the density proves to be a superimposition of normal breast tissues, sometimes referred to as a pseudomass or summation shadow, the patient can be returned to a routine screening protocol. If the finding proves to be a mass, the work-up pathway is dictated by its marnographic features. Ultrasonography is an important ad-
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Figure 6. Algorithm for evaluation of a nonpalpable mass. *Includes masses with three or fewer gentle lobulations. tlncludes masses with multiple lobulations, microlobulated margins or associated findings that are of concern, such as intermediate or suspicious calcifications.
junctive procedure in resolving indeterminate cases (Fig. 7). Oval, Round, and Gently Lobulated Circumscribed Masses
Multiple, similar, round, oval, and gently lobulated masses with circumscribed margins are probably benign and the likelihood of malignancy is less than 1%.There are three possible management strategies: (1)a routine follow-up protocol (annual ~creening)'~;(2) periodic or short-term (6-month) follow-up mammography to establish stability of the findings34;or (3) evaluation of each circumscribed mass with ultrasonography. Arguments for routine (annual) or periodic (shortterm) mammographic follow-up are based on the low probability of malignancy. found an incidence of carcinoma of 0.4% among multiple circumscribed masses at 3to 3.5-year follow-up, which is not higher
than the rate of carcinomas in the general population. For this reason, no longer advocates periodic surveillance for multiple bilateral masses unless the screening images do not portray all of the masses as having similar features. Any decision for follow-up, rather than biopsy, is based on the assumption that the masses are all similar and benign appearing. Some radiologists advocate ultrasonography as an alternative approach for evaluation of multiple circumscribed masses. The argument for ultrasound is that real-time imaging can determine which cases need further work-up and which can be assigned to routine follow-up. It should be noted, however, that a Medline literature review back to 1975 revealed no evidence-based research addressing the use of ultrasonography in these cases. An argument against routine ultrasonography is the potential generation of unnecessary biopsies. The efficacy of ultrasonography in the evaluation of multiple circumscribed masses must be documented.
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Figure 7. Ultrasonography identifies a nonpalpable mass after equivocal mammographic work-up. A and B, Craniocaudal views. A suspicious density (arrow) is identified on the left craniocaudal view (B). C and 0,Mediolateral that oblique (MLO) views. Although there are densities on the left MLO (0) might represent the mass, an exact location could not be determined. Illustration continued on opposite page
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Figure 7 (Continued). €, Left craniocaudal spot compression does not confirm the finding, suggesting that the density on the original craniocaudal view (arrow) might have been inadequately compressed fibroglandular tissue. F; Ninety-degree lateral view suggests a possible mass (arrow) in the superior aspect of the breast. G, Ultrasonography of the upper inner quadrant confirms the presence of an irregular, spiculated 1-cm mass (arrow) matching the location and size of the density in the original craniocaudal view. Ultrasonographically-guidedcore needle biopsy revealed infiltrating ductal carcinoma.
Solitary oval, round, or lobular circumscribed masses with coarse internal or rim calcifications can be characterized as benign fibroadenomas (see Fig. 5). If these typically benign calcifications are present, no further work-up is necessary. Likewise, cysts may be associated with typically benign eggshell calcifications in the periphery or gravity-dependent calcification within the cyst fluid. Round, oval, or lobular circumscribed fatcontaining masses are also benign and do not require a work-up. Examples are intramammary lymph nodes with central hilar fat,4o lipofibroadenomas,1° and evolving fat necros~s.~ Solitary or dominant oval, round, or lobulated circumscribed masses that do not have typically benign features should undergo ultrasonography. The ultrasonography examination should determine whether the mass is a simple cyst, a complex cyst, or a solid mass. If a palpable or nonpalpable mass meets the criteria for a simple cyst, no further work-up is necessary.*O On ultrasonography a typical simple cyst has circumscribed margins, sharp anterior and posterior walls, no internal echoes, and posterior enhancement (Fig. 8). When true echoes (not artifactual) are seen
within a cyst, they are usually because of proteinaceous material or cellular debris. Cyst aspiration can be performed if echogenic contents suggest a solid mass (Fig. 9). If nonbloody fluid is obtained and the cyst resolves, no further work-up is necessary. Cytologic evaluation of cyst fluid is extremely limited and is only indicated for bloody fluid aspirated from a complex cyst, if at all.* If the cyst is complex, having both cystic and solid components, an intracystic papilloma, intracystic carcinoma, or a cavitating invasive carcinoma should be in the differential diagnosis 42 If cyst aspiration is unsuccessful (Fig. or yields bloody fluid, excisional biopsy is indicated. Although pneumocystography has been used in the past to evaluate a cyst with solid components, high-resolution ( 2 7 . 5 MHz), linear array ultrasonography should provide adequate evaluation of a complex cyst in most cases. A round, oval, or gently lobulated circumscribed mass that proves to be solid by ultrasonography should be evaluated carefully to rule out carcinoma. Although ultrasonography was initially used primarily to identify simple cysts, high-resolution ultrasonography can also provide important information as to
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Figure 8. Simple cyst in a woman with a palpable mass. A, Craniocaudal view shows a palpable partially circumscribed and partially obscured mass posterior to the radiopaque marker (BB). B, Ultrasonography directly over the mass shows an oval, circumscribed mass with a sharply delineated anterior (white arrow) and posterior (black arrow) border. The mass is anechoic and there is enhancement of echoes posterior to the mass (asterisk). Typical edge refraction (cutved arrow) is seen posterior to the lateral margins of the oval mass.
the benign versus malignant differentiation of solid masses. Over the years, a number of malignant and benign features of solid masses have been reported in the imaging literat~re.~, l6 In a large clinical series, Stavros et a P reported the ultrasonographic features they found to be most reliable in differentiating malignant from benign solid masses. Malignant features include an irregular shape; angular or greater than three lobulations; microlobulated, ill-defined, or spiculated margins; anterior-to-posterior diameter (height) greater than width (taller than wide); marked hypoechogenicity; attenuating distal echoes; duct extension; and punctate calcifications (Fig. 11).Features typical of benignity include homogeneous hyperechogenicity; a thin echogenic pseudocapsule; ellipsoid shape (width greater than anterior-posterior diameter); or fewer than four gentle lobulations (Fig. 12A). To be identified as benign a solid mass should have no malignant features. Features classified as indeterminate (not helpful) are maximum diameter of the mass; echo texture (homogeneous or heterogeneous); echogenicity similar to fat; and normal or enhanced posterior echoes. It is important to understand that in this study ultrasonography was performed under real time with the operator using me-
ticulous technique and high-resolution equipment. The time taken and high quality of ultrasonography in this study does not reflect general clinical practice. Some malignancies may mimic a benign mass on ultrasonography (Fig. 12B and C).36 Additional studies need to be performed before these ultrasonography criteria are applied in general clinical practice. One recent report showed that although agreement between different readers was high for several of the ultrasonographic features, false-negative interpretations also occurred.29 At this time, it is recommended that the ultrasonographic features be incorporated into the overall assessment of the nonpalpable mass when determining the management protocol. Caution should be used, however, when a decision is made not to take a biopsy of a mass based on ultrasonographic features alone. The margins of the mass can also be evaluated with spot compression magnification mammography. If the ultrasonographic features and mammographic margin analysis favor benignity, short-term follow-up is a reasonable alternative to bi0psy.3~Opponents of short-term follow-up argue that a decision should be made for either biopsy or annual screening. The opposition to short-term fol-
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Figure 9. Aspiration of nonpalpable cyst with echogenic contents. A, Mediolateral oblique mammogram shows a partially .circumscribed and partially obscured mass. B, Ultrasonography shows a large, oval, circumscribed, echogenic mass (arrows) with enhancement of posterior echoes (asterisk).On real-time imaging the contents were felt to be characteristic of proteinaceous material within a cyst. P = pectoral muscle; R = rib. C, Image taken during ultrasound-guidedaspiration shows the needle (arrow) within the collapsing cyst. D, Image after aspiration shows needle tip (arrow) within the collapsed cyst. The thick, brown fluid was discarded.
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Figure 10. Cavitating invasive carcinoma presenting as a complex cyst. A, Craniocaudal mammogram shows a circumscribed mass (arrow) in the subareolar area. 6,Ultrasonography reveals an oval, circumscribedmass with sharply demarcated anterior and posterior borders, both solid and cystic interior, and enhanced posterior echoes (asterisk). Biopsy revealed cavitating invasive ductal carcinoma of the not otherwise specified type.
low-up cite patient anxiety, cost, and possible delay in diagnosis.30 It is important to emphasize that a number of factors can affect the decision whether to obtain a biopsy of a primarily circumscribed mass. For example, the patient's history, clinical findings, and previous mammograms are
relevant. If either mammographic or ultrasonographic features suggest malignancy, biopsy should be performed. If a solid mass is increasing in size or is not present on previous mammograms, a biopsy is usually indicated (Fig. 13). Many completely circumscribed masses can be managed with routine annual follow-up (Fig. 14). Some radiologists use size as a criterion for determining whether a circumscribed oval, round, or gently lobulated solid mass should undergo biopsy30 A survey of the Fellows of the Society of Breast Imaging indicated that whereas over 90% agreed that periodic follow-up was appropriate for circumscribed masses, over 80% listed a size (varying from 0.5 to 2 cm) above which a biopsy is recommended.'* On the other hand, did not find size to be a useful feature in determining whether a circumscribed mass warranted biopsy. Oval, Round, or Lobular Mass with Partially Circumscribed and Partially Obscured Margins
Figure 11. Solid mass with malignant ultrasoundfeatures. The mass (arrows) has an irregular shape, indistinct margins, height greater than width, and hypoechoic interior when compared with adjacent fat (F). Biopsy revealed invasive ductal carcinoma.
Additional views should be performed whenever portions of an otherwise circumscribed mass are obscured by overlying or adjacent breast tissue. Spot compression
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Figure 12. A 35-year-oldwoman with a history of previous excisional biopsy of a fibroadenoma in the right breast felt a new mobile mass in the upper outer quadrant of each breast. Mammograms failed to depict the masses and ultrasonography was performed. A, Left breast. The 1-cm mass (arrows) is oval (ellipsoid), wider than tall, circumscribed with a thin echogenic pseudocapsule, gently bilobulated, isoechoic compared with nearby fat (F), and has no effect on posterior echoes. B, Right breast. The 1-cm mass (arrows) is also oval (ellipsoid), wider than tall, circumscribed, isoechoic compared with adjacent fat (F), and no effect on posterior echoes. Note that the margins are not as well demarcated on the anterior border when compared with the mass in A. C,Three months later, the patient reported that the right breast mass had increased in size. The mass (arrows) is now larger and the margins are microlobulated. The mass is hypoechoic relative to adjacent fat (F). Biopsy was recommended. 0, Postfire image during ultrasonography-guidedcore needle biopsy of right breast mass shows 14-gauge core needle biopsy traversing the mass (arrow). Biopsy of the right mass (B-0) revealed medullary carcinoma. Subsequent biopsy of left breast mass (A) revealed fibroadenoma.
views generally displace the tissue from a circumscribed mass. Ultrasonography should be performed if the mass is possibly a cyst. If the spot compression views or ultrasonography show a mass with ill-defined or spiculated margins, a biopsy should be recommended (Fig. 15). The number of lobulations on the contour of a mass should be considered in the evaluation. A few gentle lobulations are of less concern than multiple lobulations on mammography or ultrasonography (Fig. 16). Stavros et a138reported that for a mass to be characterized as benign on ultrasonography it should have three or less gentle lobulations. Irregular Mass with Ill-Defined or Spiculated Margins
These margins are suspicious or highly suggestive of malignancy on mammography and
biopsy should be performed (see Fig. 15). U1trasonography is not necessary to determine the need for biopsy. It is appropriate to perform ultrasonography in such cases, however, to determine whether an ultrasonographyguided needle biopsy or prebiopsy needle localization can be performed.16,28 PALPABLE MASSES
The imaging work-up of a palpable mass has several purposes: (1)to define better the nature of the mass, (2) to detect unexpected ipsilateral or contralateral cancer, and (3) to identify a nonpalpable extensive intraductal component to reduce the possibility of recurrence after breast conservation therapy (Fig. 17).21,25 It should be emphasized that the purpose of mammography is not to defer biopsy of a clinically suspicious mass.1z,27
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Figure 13. Carcinoma presenting as a neodensity. Mediolateral oblique mammograms from two consecutive annual screening examinations. A, The most recent examination revealed numerous circumscribed densities in the upper breast, consistent with lymph nodes. One small mass (arrow) could not be identified on the screening examination performed one year before. B, Screening examination performed one year prior. C,Spot compression view of the neodensity (arrow) reveals partially circumscribed and partially illdefined margins. The mass could not be seen on ultrasonography and was therefore assumed to be solid. Stereotactically guided core needle biopsy was recommended. D, Postbiopsy image shows the defect (arrow) from the 11-gauge vacuum-assisted directional biopsy device. Histologic diagnosis was invasive lobular carcinoma.
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Figure 14. Circumscribed mass (arrow) in upper outer breast was considered benign, probably an intramammary lymph node based on the location and (hilar) notch. Routine annual mammograms showed no change in the mass.
Figure 15. Oval mass with ill-defined margins. A, Mediolateral oblique view shows a round to oval mass (arrow) in the subareolar region. Margins were difficult to assess because of adjacent breast tissue but were suspected to be ill defined. 6,Spot compression, magnification views confirm that the margins are ill defined, and biopsy was recommended. There is a solitary, benign coarse calcification anterior to the mass.
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A basic algorithm guideline for the evaluation of a palpable mass is presented in Figure 18. Before performing mammography, a correlative breast examination should be performed. The correlative examination is directed specifically to the area of concern, identified either by the referring health care provider or the patient? The correlative examination verifies the presence of the palpable mass, and a radiopaque marker (BB) is placed on the surface of the breast so that the BB is directly over the mass in each of the
Figure 17. Palpable carcinoma with extensive intraductal carcinoma. The palpable mass (asterisk) is irregular and spiculated, leading to a final assessment highly suggestive of malignancy. The mammogram also showed extensive calcifications of ductal carcinoma in situ, which was nonpalpable. Adequate treatment mandated removal of all of the mammographically detected calcifications as well as the palpable carcinoma.
mammographic projections. To accomplish this, the position of the BB should be adjusted for each projection so that the BB and the palpable mass are superimposed on the film (Figure 19).22Spot compression or tangential views may be indicated when the mass is superimposed on dense fibroglandular tissue (Fig. 20). Palpable Mass Not Visible on Mammography
Figure 16. Mass with numerous lobulation. Craniocaudal (A) and close up of rnediolateral oblique view (6) show a palpable mass with numerous lobulations. The margins were partially circumscribed and partially obscured. The radiopaque marker (BB) had been placed on the Skin overlying the mass. Biopsy revealed phyllodes tumor.
If the palpable mass is not seen or if the mass is oval or round with partially circumscribed margins, the patient should be evaluated with ultrasonography. If the mass is a simple cyst on ultrasonography, the patient can be manged with a routine screening protocol (see Fig. 8). If the cyst is painful, of concern to the patient, or echogenic (internal echoes or features that suggest possible solid components), cyst aspiration can be performed. As mentioned previously, cytologic evaluation of the cyst fluid is not recommended unless it is bloody or dark red.s If the palpable mass is solid at ultrasonography, a tissue diagnosis is warranted. The value of a needle biopsy of a palpable solid mass depends on the contribution it makes to the management plan. If the patient Or her physician has decided to have the pa'pable maSS excised regardless Of needle biopsy results, it can be argued that the needle
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Figure 18. Algorithm for evaluation of a palpable mass in a woman 30 years of age or older. *Includes masses with a 3 or fewer gentle lobulations. tlncludes masses with multiple lobulations, rnicrolobulated margins or other associated findings of concern, such as intermediate or higher probability of malignancy calcifications.
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Figure 19. Radiopaque marker (BB) placed on the surface of the breast to identify the exact location of a palpable mass. A, Craniocaudal view. The BB is placed on the superior surface of the breast directly over the palpable mass (arrow). 6,Mediolateral oblique view. The BB is now placed on the medial surface of the breast so it will be as close as possible to the palpable mass (arrow) on the mediolateral oblique view.
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Figure 20. Tangential view used to depict palpable mass not visible on routine mammography views. A, Mediolateral oblique view with radiopaque metallic marker (66)directly over the palpable mass fails to show an abnormality within the overlying dense fibroglandular tissue. B, View tangential to the palpable mass (arrow) casts it over subcutaneous fat, allowing it to be seen. The mass is oval and circumscribed. C,Ultrasonography directly over the palpable mass shows an oval, circumscribed mass with width greater than anterior-posterior diameter. Fine needle aspiration biopsy showed fibroadenoma, concordant with imaging findings. The patient elected not TO have the small mass excised and it has been stable for 10 years.
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biopsy just adds cost to the work-up without contributing to management decisions. In the case of a mammographically or ultrasonographically benign-appearing mass, however, the patient and her physician may defer open biopsy if a needle biopsy confirms a benign diagnosis. An example is a circumscribed, oval mass that proves to be a fibroadenoma at needle biopsy. In this situation, the needle biopsy is a reasonable procedure. If the mass is ill-defined or has suspicious features on ultrasonography, a tissue diagnosis is mandatory (Fig. 21). Then, the value of a needle biopsy has to be questioned. Oval, Round, or Lobular Palpable Mass with Circumscribed and Partially Obscured Margins Additional views and spot compression magnification views can be performed to evaluate the margins better. Again, ultrasonography is performed to rule out a simple cyst. If the work-up reveals an irregular shape or ill-defined margins, excision of the mass is indicated (Fig. 22). Irregular Mass with Ill-Defined or Spiculated Margins Because the mass is palpable and likely malignant, the value of a needle biopsy depends on the management protocol of the surgeon. In a one-step procedure, open biopsy and frozen section are followed immediately by the appropriate surgical treatment.31 In a two-step procedure, the biopsy is performed first, followed by definitive surgery at a later date. In the latter situation, a preoperative core needle biopsy of a suspected carcinoma can provide information about histologic type, invasion, tumor grade, and hormone receptor status that could affect overall management. Imaging-guided core needle biopsy or preoperative needle localization is appropriate if the mass is difficult to palpate but clearly visualized on imaging. PALPABLE MASSES IN WOMEN LESS THAN 30 YEARS OF AGE The recommended work-up of a palpable breast mass is modified for women under 30 years of age because of the lower sensitivity of mammography (Fig. 23). There is consider-
Figure 21. Palpable mass with vague asymmetric density on mammography and suspicious mass on ultrasonography. A, Mediolateral oblique mammogram shows only an asymmetric density (arrow) at the location of the palpable mass, identified by the radiopaque marker (BB). B, Ultrasonography directly over the palpable mass (arrows) shows an irregular shape, ill-defined margins and hypoechoic interior. Ultrasound-guidedcore needle biopsy revealed invasive ductal carcinoma, not otherwise specified type.
able documentation that mammography is less effective in younger women.6 The lower sensitivity of mammography in younger women is caused by the greater likelihood of dense breast tissue c o m p ~ s i t i o n .Approxi~~ mately 30% of women under 35, however, have a primarily fatty breast tissue composition. In addition, the incidence of breast carcinoma is lower in women under 40 years of age. For these reasons, mammography screening is not recommended in this age group unless the woman is at high risk for breast carcinoma. Nonetheless, breast carcinomas do occur in this age group and a complete workup of palpable masses should be done. In
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Figure 22. Palpable mass with ill-defined or spiculated margins on mammography. A, Mediolateral oblique mammogram shows a round mass with ill-defined and spiculated margins at the location of a palpable mass identified by the radiopaque marker (BB). B, Craniocaudal mammogram confirms that the suspicious mass (arrow) matches the palpable abnormality. An asymmetric density (arrowhead) medial to the mass could not be reproduced on other projections and was determined to be overlapping fibroglandular tissue. Excision of the mass revealed invasive ductal carcinoma.
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Figure 23. Algorithm for evaluation of a palpable mass in a woman 30 years of age or younger.
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Figure 24. Palpable mass in a 28-year-old woman. Ultrasonography was the initial imaging examination. A, Ultrasonography of the palpable abnormality reveals a mass with irregular shape, ill-defined margins and low level, heterogeneous internal echoes. Craniocaudal (B) and mediolateral oblique (C) mammograms were then performed with a radiopaque marker (BB) placed over the palpable mass and adjusted for each view. The mammograms showed an ill-defined mass (arrow) that matched the site of the palpable abnormality. No other suspicious findings were identified. Biopsy revealed infiltrating ductal carcinoma.
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women under the age of 30, ultrasonography is the preferred initial imaging modality for the evaluation of a palpable mass.', If ultrasonography identifies a suspicious abnormality/ mammography should be performed to identify possible multifocal lesions or an intraductal component of an invasive tumor (Fig. 24). As in any age group, protocols should be tailored to the individual clinical problem. References 1. American College of Radiology: Appropriateness Criteria, vol2. Reston, VA, American College of Radiology, 1996 2. American College of Radiology: Breast Imaging Reporting and Data System (BI-RADS), ed 3. Reston, VA, American College of Radiology, 1998 3. Bassett LW, Gold RH, Cove HC: Mammographic spectrum of traumatic fat necrosis: The fallibility of "pathognomonic" signs of carcinoma. AJR Am J Roentgenol 130:119-122, 1987 4. Bassett LW, Hendrick RE, Bassford TL, et al: Quality Determinants of Mammography. Clinical Practice Guideline, No. 13. AHCPR Publication No. 95-0632. Rockville, MD, Agency for Health Care Policy and Research, Public Health Service, US Department of Health and Human Services, 1994 5. Bassett LW, Ysrael M, Gold RH, et al: Usefulness of mammography and sonography in women less than 35 years of age. Radiology 180:831-835, 1991 6. Bennett IC, Freitas R Jr, Fentiman IS: Diagnosis of breast cancer in young women. Aust N Z J Surg 61:284-289, 1991 7. Berkowitz JE, Gatewood MB, Gayler BW: Equivocal mammographic findings: Evaluation with spot compression. Radiology 171:369-371, 1989 8. Ciatto S, Cariaggi P, Bularesi P: The value of routine cytologic examination of breast cyst fluids. Acta Cyto1 31:301-304, 1987 9. Cole-Beuglet C, Soriano RZ, Kurtz AB, et al: Fibroadenoma of the breast: Sonomammography correlated with pathology in 122 patients. AJR Am J Roentgenol 140:369-375, 1983 10. Crothers JG, Butler NF, Fortt RW, et al: Fibroadenolipoma of the breast. Br J Radiol 48:191-202, 1985 11. DOrsi CJ, Kopans DB: Mammographic feature analysis. Semin Roentgenol 28:204-230, 1993 12. Edeiken S: Mammography in the symptomatic woman. Cancer 63:1412-1414, 1989 13. Evans WP: Breast masses: Appropriate evaluation. Radiol Clin North Am 33:1085-1108, 1995 14. Feig SA: Importance of supplementary mammographic views to diagnostfp accuracy.-AJR Am J Roentgenol 151:4041, 1988 15. Fomage BD, Coan JD, David CL: Ultrasound-guided needle biopsy of the breast and other interventional procedures. Radiol Clin North Am 30:167-185, 1992 16. Fornage BD, Lorigan JG, Andry E: Fibroadenoma of the breast: Sonographic appearance. Radiology 172:671-675, 1989 17. Gold RH, Montgomery CK, Rambo ON: Significance of margination of benign and malignant infiltrative mammary lesions: Roentgenologic-pathologic correlation. AJR Am J Roentgenol 118:881-894, 1973
18. Hall FM: Statistics, opinions and controversies among expert mammographers. Breast Dis 6:173, 1993 19. Hillman BJ: New imaging technology and cost containment. AJR Am J Roentgenol 162503-506, 1994 20. Hilton SV, Leopold GR, Olson LK, et al: Real-time breast sonography: Application in 300 consecutive patients. AJR Am J Roentgenol 147:479436, 1986 21. Holland R, Connolly JL, Gelman R, et al: The presence of an extensive intraductal component following a limited resection correlates with prominent residual disease in the remainder of the breast. J Clin Oncol 8:113-118, 1990 22. Homer MJ: Proper placement of a metallic marker on an area of concern in the breast. AJR Am J Roentgenol 16739S391, 1996 23. Jackson VP, Dines KA, Bassett LW, et al: Diagnostic importance of radiographic density of noncalcified breast masses: Analysis of 91 lesions. AJR Am J Roentgenol 15725-28, 1991 24. Kerlikowske K, Grady D, Barclay J, et al: Effect of age, breast density, and family history on the sensitivity of first screening mammography. JAMA 2673338, 1996 25. Kopans DB, Meyer JE, Cohen AM, et al: Palpable breast masses: The importance of preoperative mammography. JAMA 246:2819-1823, 1981 26. Love SM, McGuigan KA, Chap L: The Revlon/UCLA Breast Center Practice Guidelines for the Treatment of Breast Disease. The Cancer Journal 22-15, 1996 27. Mann BD, Giuliano AE, Bassett LW, et al: Delayed diagnosis of breast cancer as a result of normal mammograms. Arch Surg 118:23-24, 1983 28. Parker SH, Jobe WE, Dennis MA, et al: US-guided automated large core breast biopsy. Radiology 187507-511, 1993 29. Rahbar G, Sie AC, Hansen GC, et a1 Ultrasonographic differentiation of benign vs. malignant solid breast masses. Radiology 213:889-894, 1999 30. Rubin E: Six-month follow-up: An alternative view. Radiology 213:15-18, 1999 31. Scanlon EF: The case for and against two-step procedures for the surgical treatment of breast cancer. Cancer 53:677-680, 1984 32. Sickles EA: Efficacy of spot compression-magnification and tangential views in mammographic evaluation of palpable breast masses. Radiology 185:87-90, 1992 33. Sickles E A Nonpalpable, circumscribed, noncalcified solid breast masses: Likelihood of malignancy based on lesion size and age of patient. Radiology 192:439442, 1994 34. Sickles EA: Periodic mammographic follow-up of probably benign lesions: Results in 3,184 consecutive cases. Radiology 179:463-468, 1991 35. Sickles E A Probably benign breast lesions: When should follow-up be recommended and what is the optimal follow-up protocol? Radiology 213:ll-14, 1999 36. Skaane P, Engedal K Analysis of sonographic features in the differentiation of fibroadenoma and invasive ductal carcinoma. AJR Am J Roentgenol 170:109114, 1998 37. So0 MS, Williford ME, Walsh R, et al: Papillary carcinoma of the breast: Imaging findings. AJR Am J Roentzenol 164321-326. 1995 38. Stavr; AT, Thickman D, Rapp CL, et al: Solid breast nodules: Use of sonography to distinguish between
IMAGING OF BREAST MASSES benign and malignant lesions. Radiology 196:123134, 1995 39. Sunshine JH, McNeil BJ: Rapid method for rigorous assessment of radiologic imaging technologies. Radiology 202:549-557, 1997 40. Svane G, Franzen S: Radiologic appearance of nonpalpable intramammary lymph nodes. Acta Radio1 34:577-580, 1993
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41. Woolf SH: AHCPR Interim Manual for Clinical Practice Guideline Development. No. 91-0018. Rockville, MD, Agency for Health Care Policy and Research, US Department of Health and Human Services, 1991 42. Yang WT, 5uen M, Metreweli C: Sonographic features of benign papillary neoplasms of the breast: Review of 22 patients. J Ultrasound Med 16:161-168,1997 Address reprint requests to Lawrence W. Bassett, MD 200 UCLA Medical Plaza, Rm 165-47 Box 956952 Los Angeles, CA 90095-6952
e-mail:[email protected]
0033-8389/00 $15.00
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.OO
IMAGING OF BREAST MASSES Lawrence W. Bassett, MD
Standardized terminology has been developed for the description of masses depicted on mammography and similar systems are under development for breast ultrasonography and breast MR imaging. The use of standardized terminology improves the communication of findings and management recommendations. It also facilitates assessment of the effectiveness of screening through medical audits. For this reason, the standardized terminology of the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS)' has been incorporated into this article on breast masses. The article places an emphasis on the evidence-based approach to the appropriate evaluation and management of breast masses, sometimes referred to as appropriateness guidelines.' The evidence-based approach relies on peer-reviewed published research in scientific journals rather than traditional approaches or the anecdotal experiences of individual practitioners.26The ability to compare and combine the results of published clinical research studies is essential to the development of evidence-based appropriateness guidelines. The use of standardized terminology in the radiology literature also facilitates the development of these guidelines. When published research studies do not address a specific clinical situation, appropriateness guidelines are based on a consensus of a panel of expert^.^' In addition to the use of the most effective imaging technology, appropriateness guidelines
should meet cost-effectiveness criteria. There should be a reasonable likelihood that the information obtained from additional workup will affect management decisions and that the proposed work-up is the least expensive 39 method to get the essential inf~rmation.'~, Because other articles in this issue address novel technologies, the focus of this article is on mammography and sonography for the evaluation of breast masses. The organization of the article also reflects some differences in the management of nonpalpable masses, palpable masses in women over the age of 30, and palpable masses in women under the age of 30. STANDARDIZED DESCRIPTION OF MAMMOGRAPHIC FEATURES
In the ACR BI-RADS,' a mass is defined as a space-occupying lesion seen in at least two projections. If seen in only one projection, a suspected mass is called a density. The mass could be obscured by breast tissues on other views or it could represent a pseudomass created by superimposition of tissues (Fig. 1). Further work-up determines the real nature of the finding. In standardized terminology, the mammographic features of a verified mass include its shape, margins, density, size, location, and any associated features. The shape of a mass can be described as round, oval, lobular, or
From the Department of Radiological Sciences, University of California Los Angeles School of Medicine, Los Angeles, California
RADIOLOGIC CLINICS OF NORTH AMERICA
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Figure 1. Density due to superimposed normal tissues. A, Mediolateral oblique view shows a possible irregular, spiculated mass (arrow) in the upper breast. B, Craniocaudal view does not confirm the presence of a mass. C,Ninety-degree lateral view shows no mass. 0,Spot compression of upper breast in mediolateral oblique projection indicates that the density represents a superimposition of normal tissues.
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Figure 2. Terminology used to describe the shape of a mass.
irregular (Fig. 2). The margins of a mass, generally recognized as the most reliable feature in determining the likelihood of malignancy,17 can be described as circumscribed; microlobulated; obscured; ill-defined (indistinct); or
spiculated (Fig. 3). When the margins are not uniform throughout, the descriptor indicating the portion of greatest concern should generally be used.l* If the mass is mostly circumscribed but not completely visualized because
Figure 3. Terminology used to describe the margins of a mass.
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of adjacent tissue of similar density, the term obscured is applied. The density or radiographic attenuation of the mass relative to an equal volume of normal fibroglandular tissue is often included in the description. Appropriate terms are highdensity; equal density (isodense);low density; or fat-containing (radiolucent). Although carcinomas are usually of high density, some are isodense or low in density. This feature is not always reliable. On the other hand, fat within the actual confines of a mass is a reliable sign of benignity (Fig. 4). Other findings that are useful in identifying the nature of a mass include associated findings, such as calcifications (Fig. 5), skin retraction, skin thickening, and ipsilateral lymph node enlargement. As a general rule, the most ominous of the features should be used to determine the final description and assessment of the rnass.I* In the evaluation of masses, the final assessment is often determined by a combination of the mammographic, ultrasonographic, and clinical findings.
Figure 5. Typical coarse, rim calcification identifies this mass as a benign fibroadenoma.
NONPALPABLE MASSES Nonpalpable masses are usually identified as a result of screening mammography or as an incidental finding on a diagnostic examination. Figure 6 provides a suggested algorithm for the work-up of a nonpalpable mass. The pathways in the work-up protocol should be evidence-based whenever possible. Of course, the algorithm may need to be adjusted for individual patients and their clinical histories. Density: Mass Versus Pseudomass or Summation Shadows
Figure 4. Fat-containing mass. The patient felt a subareolar mass. Craniocaudal mammogram reveals a mass (arrows) containing fat and fibroglandular tissue density elements. The findings are pathognomonic for lipofibroadenoma, a benign mass requiring no further workup.
As illustrated in Figure 1, if a suspected mass is seen on the mediolateral oblique or craniocaudal view but cannot be confirmed on the other standard projection, it is usually referred to as a density. Additional imaging should be performed to confirm that a mass is truly present. The additional imaging may include a 90-degree lateral view; spot compression; roll views (e.g., the breast is rolled medially .or laterally for the craniocaudal view); and tangential views.7,14, 32 If the density proves to be a superimposition of normal breast tissues, sometimes referred to as a pseudomass or summation shadow, the patient can be returned to a routine screening protocol. If the finding proves to be a mass, the work-up pathway is dictated by its marnographic features. Ultrasonography is an important ad-
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Figure 6. Algorithm for evaluation of a nonpalpable mass. *Includes masses with three or fewer gentle lobulations. tlncludes masses with multiple lobulations, microlobulated margins or associated findings that are of concern, such as intermediate or suspicious calcifications.
junctive procedure in resolving indeterminate cases (Fig. 7). Oval, Round, and Gently Lobulated Circumscribed Masses
Multiple, similar, round, oval, and gently lobulated masses with circumscribed margins are probably benign and the likelihood of malignancy is less than 1%.There are three possible management strategies: (1)a routine follow-up protocol (annual ~creening)'~;(2) periodic or short-term (6-month) follow-up mammography to establish stability of the findings34;or (3) evaluation of each circumscribed mass with ultrasonography. Arguments for routine (annual) or periodic (shortterm) mammographic follow-up are based on the low probability of malignancy. found an incidence of carcinoma of 0.4% among multiple circumscribed masses at 3to 3.5-year follow-up, which is not higher
than the rate of carcinomas in the general population. For this reason, no longer advocates periodic surveillance for multiple bilateral masses unless the screening images do not portray all of the masses as having similar features. Any decision for follow-up, rather than biopsy, is based on the assumption that the masses are all similar and benign appearing. Some radiologists advocate ultrasonography as an alternative approach for evaluation of multiple circumscribed masses. The argument for ultrasound is that real-time imaging can determine which cases need further work-up and which can be assigned to routine follow-up. It should be noted, however, that a Medline literature review back to 1975 revealed no evidence-based research addressing the use of ultrasonography in these cases. An argument against routine ultrasonography is the potential generation of unnecessary biopsies. The efficacy of ultrasonography in the evaluation of multiple circumscribed masses must be documented.
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Figure 7. Ultrasonography identifies a nonpalpable mass after equivocal mammographic work-up. A and B, Craniocaudal views. A suspicious density (arrow) is identified on the left craniocaudal view (B). C and 0,Mediolateral that oblique (MLO) views. Although there are densities on the left MLO (0) might represent the mass, an exact location could not be determined. Illustration continued on opposite page
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Figure 7 (Continued). €, Left craniocaudal spot compression does not confirm the finding, suggesting that the density on the original craniocaudal view (arrow) might have been inadequately compressed fibroglandular tissue. F; Ninety-degree lateral view suggests a possible mass (arrow) in the superior aspect of the breast. G, Ultrasonography of the upper inner quadrant confirms the presence of an irregular, spiculated 1-cm mass (arrow) matching the location and size of the density in the original craniocaudal view. Ultrasonographically-guidedcore needle biopsy revealed infiltrating ductal carcinoma.
Solitary oval, round, or lobular circumscribed masses with coarse internal or rim calcifications can be characterized as benign fibroadenomas (see Fig. 5). If these typically benign calcifications are present, no further work-up is necessary. Likewise, cysts may be associated with typically benign eggshell calcifications in the periphery or gravity-dependent calcification within the cyst fluid. Round, oval, or lobular circumscribed fatcontaining masses are also benign and do not require a work-up. Examples are intramammary lymph nodes with central hilar fat,4o lipofibroadenomas,1° and evolving fat necros~s.~ Solitary or dominant oval, round, or lobulated circumscribed masses that do not have typically benign features should undergo ultrasonography. The ultrasonography examination should determine whether the mass is a simple cyst, a complex cyst, or a solid mass. If a palpable or nonpalpable mass meets the criteria for a simple cyst, no further work-up is necessary.*O On ultrasonography a typical simple cyst has circumscribed margins, sharp anterior and posterior walls, no internal echoes, and posterior enhancement (Fig. 8). When true echoes (not artifactual) are seen
within a cyst, they are usually because of proteinaceous material or cellular debris. Cyst aspiration can be performed if echogenic contents suggest a solid mass (Fig. 9). If nonbloody fluid is obtained and the cyst resolves, no further work-up is necessary. Cytologic evaluation of cyst fluid is extremely limited and is only indicated for bloody fluid aspirated from a complex cyst, if at all.* If the cyst is complex, having both cystic and solid components, an intracystic papilloma, intracystic carcinoma, or a cavitating invasive carcinoma should be in the differential diagnosis 42 If cyst aspiration is unsuccessful (Fig. or yields bloody fluid, excisional biopsy is indicated. Although pneumocystography has been used in the past to evaluate a cyst with solid components, high-resolution ( 2 7 . 5 MHz), linear array ultrasonography should provide adequate evaluation of a complex cyst in most cases. A round, oval, or gently lobulated circumscribed mass that proves to be solid by ultrasonography should be evaluated carefully to rule out carcinoma. Although ultrasonography was initially used primarily to identify simple cysts, high-resolution ultrasonography can also provide important information as to
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Figure 8. Simple cyst in a woman with a palpable mass. A, Craniocaudal view shows a palpable partially circumscribed and partially obscured mass posterior to the radiopaque marker (BB). B, Ultrasonography directly over the mass shows an oval, circumscribed mass with a sharply delineated anterior (white arrow) and posterior (black arrow) border. The mass is anechoic and there is enhancement of echoes posterior to the mass (asterisk). Typical edge refraction (cutved arrow) is seen posterior to the lateral margins of the oval mass.
the benign versus malignant differentiation of solid masses. Over the years, a number of malignant and benign features of solid masses have been reported in the imaging literat~re.~, l6 In a large clinical series, Stavros et a P reported the ultrasonographic features they found to be most reliable in differentiating malignant from benign solid masses. Malignant features include an irregular shape; angular or greater than three lobulations; microlobulated, ill-defined, or spiculated margins; anterior-to-posterior diameter (height) greater than width (taller than wide); marked hypoechogenicity; attenuating distal echoes; duct extension; and punctate calcifications (Fig. 11).Features typical of benignity include homogeneous hyperechogenicity; a thin echogenic pseudocapsule; ellipsoid shape (width greater than anterior-posterior diameter); or fewer than four gentle lobulations (Fig. 12A). To be identified as benign a solid mass should have no malignant features. Features classified as indeterminate (not helpful) are maximum diameter of the mass; echo texture (homogeneous or heterogeneous); echogenicity similar to fat; and normal or enhanced posterior echoes. It is important to understand that in this study ultrasonography was performed under real time with the operator using me-
ticulous technique and high-resolution equipment. The time taken and high quality of ultrasonography in this study does not reflect general clinical practice. Some malignancies may mimic a benign mass on ultrasonography (Fig. 12B and C).36 Additional studies need to be performed before these ultrasonography criteria are applied in general clinical practice. One recent report showed that although agreement between different readers was high for several of the ultrasonographic features, false-negative interpretations also occurred.29 At this time, it is recommended that the ultrasonographic features be incorporated into the overall assessment of the nonpalpable mass when determining the management protocol. Caution should be used, however, when a decision is made not to take a biopsy of a mass based on ultrasonographic features alone. The margins of the mass can also be evaluated with spot compression magnification mammography. If the ultrasonographic features and mammographic margin analysis favor benignity, short-term follow-up is a reasonable alternative to bi0psy.3~Opponents of short-term follow-up argue that a decision should be made for either biopsy or annual screening. The opposition to short-term fol-
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Figure 9. Aspiration of nonpalpable cyst with echogenic contents. A, Mediolateral oblique mammogram shows a partially .circumscribed and partially obscured mass. B, Ultrasonography shows a large, oval, circumscribed, echogenic mass (arrows) with enhancement of posterior echoes (asterisk).On real-time imaging the contents were felt to be characteristic of proteinaceous material within a cyst. P = pectoral muscle; R = rib. C, Image taken during ultrasound-guidedaspiration shows the needle (arrow) within the collapsing cyst. D, Image after aspiration shows needle tip (arrow) within the collapsed cyst. The thick, brown fluid was discarded.
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Figure 10. Cavitating invasive carcinoma presenting as a complex cyst. A, Craniocaudal mammogram shows a circumscribed mass (arrow) in the subareolar area. 6,Ultrasonography reveals an oval, circumscribedmass with sharply demarcated anterior and posterior borders, both solid and cystic interior, and enhanced posterior echoes (asterisk). Biopsy revealed cavitating invasive ductal carcinoma of the not otherwise specified type.
low-up cite patient anxiety, cost, and possible delay in diagnosis.30 It is important to emphasize that a number of factors can affect the decision whether to obtain a biopsy of a primarily circumscribed mass. For example, the patient's history, clinical findings, and previous mammograms are
relevant. If either mammographic or ultrasonographic features suggest malignancy, biopsy should be performed. If a solid mass is increasing in size or is not present on previous mammograms, a biopsy is usually indicated (Fig. 13). Many completely circumscribed masses can be managed with routine annual follow-up (Fig. 14). Some radiologists use size as a criterion for determining whether a circumscribed oval, round, or gently lobulated solid mass should undergo biopsy30 A survey of the Fellows of the Society of Breast Imaging indicated that whereas over 90% agreed that periodic follow-up was appropriate for circumscribed masses, over 80% listed a size (varying from 0.5 to 2 cm) above which a biopsy is recommended.'* On the other hand, did not find size to be a useful feature in determining whether a circumscribed mass warranted biopsy. Oval, Round, or Lobular Mass with Partially Circumscribed and Partially Obscured Margins
Figure 11. Solid mass with malignant ultrasoundfeatures. The mass (arrows) has an irregular shape, indistinct margins, height greater than width, and hypoechoic interior when compared with adjacent fat (F). Biopsy revealed invasive ductal carcinoma.
Additional views should be performed whenever portions of an otherwise circumscribed mass are obscured by overlying or adjacent breast tissue. Spot compression
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Figure 12. A 35-year-oldwoman with a history of previous excisional biopsy of a fibroadenoma in the right breast felt a new mobile mass in the upper outer quadrant of each breast. Mammograms failed to depict the masses and ultrasonography was performed. A, Left breast. The 1-cm mass (arrows) is oval (ellipsoid), wider than tall, circumscribed with a thin echogenic pseudocapsule, gently bilobulated, isoechoic compared with nearby fat (F), and has no effect on posterior echoes. B, Right breast. The 1-cm mass (arrows) is also oval (ellipsoid), wider than tall, circumscribed, isoechoic compared with adjacent fat (F), and no effect on posterior echoes. Note that the margins are not as well demarcated on the anterior border when compared with the mass in A. C,Three months later, the patient reported that the right breast mass had increased in size. The mass (arrows) is now larger and the margins are microlobulated. The mass is hypoechoic relative to adjacent fat (F). Biopsy was recommended. 0, Postfire image during ultrasonography-guidedcore needle biopsy of right breast mass shows 14-gauge core needle biopsy traversing the mass (arrow). Biopsy of the right mass (B-0) revealed medullary carcinoma. Subsequent biopsy of left breast mass (A) revealed fibroadenoma.
views generally displace the tissue from a circumscribed mass. Ultrasonography should be performed if the mass is possibly a cyst. If the spot compression views or ultrasonography show a mass with ill-defined or spiculated margins, a biopsy should be recommended (Fig. 15). The number of lobulations on the contour of a mass should be considered in the evaluation. A few gentle lobulations are of less concern than multiple lobulations on mammography or ultrasonography (Fig. 16). Stavros et a138reported that for a mass to be characterized as benign on ultrasonography it should have three or less gentle lobulations. Irregular Mass with Ill-Defined or Spiculated Margins
These margins are suspicious or highly suggestive of malignancy on mammography and
biopsy should be performed (see Fig. 15). U1trasonography is not necessary to determine the need for biopsy. It is appropriate to perform ultrasonography in such cases, however, to determine whether an ultrasonographyguided needle biopsy or prebiopsy needle localization can be performed.16,28 PALPABLE MASSES
The imaging work-up of a palpable mass has several purposes: (1)to define better the nature of the mass, (2) to detect unexpected ipsilateral or contralateral cancer, and (3) to identify a nonpalpable extensive intraductal component to reduce the possibility of recurrence after breast conservation therapy (Fig. 17).21,25 It should be emphasized that the purpose of mammography is not to defer biopsy of a clinically suspicious mass.1z,27
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Figure 13. Carcinoma presenting as a neodensity. Mediolateral oblique mammograms from two consecutive annual screening examinations. A, The most recent examination revealed numerous circumscribed densities in the upper breast, consistent with lymph nodes. One small mass (arrow) could not be identified on the screening examination performed one year before. B, Screening examination performed one year prior. C,Spot compression view of the neodensity (arrow) reveals partially circumscribed and partially illdefined margins. The mass could not be seen on ultrasonography and was therefore assumed to be solid. Stereotactically guided core needle biopsy was recommended. D, Postbiopsy image shows the defect (arrow) from the 11-gauge vacuum-assisted directional biopsy device. Histologic diagnosis was invasive lobular carcinoma.
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Figure 14. Circumscribed mass (arrow) in upper outer breast was considered benign, probably an intramammary lymph node based on the location and (hilar) notch. Routine annual mammograms showed no change in the mass.
Figure 15. Oval mass with ill-defined margins. A, Mediolateral oblique view shows a round to oval mass (arrow) in the subareolar region. Margins were difficult to assess because of adjacent breast tissue but were suspected to be ill defined. 6,Spot compression, magnification views confirm that the margins are ill defined, and biopsy was recommended. There is a solitary, benign coarse calcification anterior to the mass.
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A basic algorithm guideline for the evaluation of a palpable mass is presented in Figure 18. Before performing mammography, a correlative breast examination should be performed. The correlative examination is directed specifically to the area of concern, identified either by the referring health care provider or the patient? The correlative examination verifies the presence of the palpable mass, and a radiopaque marker (BB) is placed on the surface of the breast so that the BB is directly over the mass in each of the
Figure 17. Palpable carcinoma with extensive intraductal carcinoma. The palpable mass (asterisk) is irregular and spiculated, leading to a final assessment highly suggestive of malignancy. The mammogram also showed extensive calcifications of ductal carcinoma in situ, which was nonpalpable. Adequate treatment mandated removal of all of the mammographically detected calcifications as well as the palpable carcinoma.
mammographic projections. To accomplish this, the position of the BB should be adjusted for each projection so that the BB and the palpable mass are superimposed on the film (Figure 19).22Spot compression or tangential views may be indicated when the mass is superimposed on dense fibroglandular tissue (Fig. 20). Palpable Mass Not Visible on Mammography
Figure 16. Mass with numerous lobulation. Craniocaudal (A) and close up of rnediolateral oblique view (6) show a palpable mass with numerous lobulations. The margins were partially circumscribed and partially obscured. The radiopaque marker (BB) had been placed on the Skin overlying the mass. Biopsy revealed phyllodes tumor.
If the palpable mass is not seen or if the mass is oval or round with partially circumscribed margins, the patient should be evaluated with ultrasonography. If the mass is a simple cyst on ultrasonography, the patient can be manged with a routine screening protocol (see Fig. 8). If the cyst is painful, of concern to the patient, or echogenic (internal echoes or features that suggest possible solid components), cyst aspiration can be performed. As mentioned previously, cytologic evaluation of the cyst fluid is not recommended unless it is bloody or dark red.s If the palpable mass is solid at ultrasonography, a tissue diagnosis is warranted. The value of a needle biopsy of a palpable solid mass depends on the contribution it makes to the management plan. If the patient Or her physician has decided to have the pa'pable maSS excised regardless Of needle biopsy results, it can be argued that the needle
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Figure 18. Algorithm for evaluation of a palpable mass in a woman 30 years of age or older. *Includes masses with a 3 or fewer gentle lobulations. tlncludes masses with multiple lobulations, rnicrolobulated margins or other associated findings of concern, such as intermediate or higher probability of malignancy calcifications.
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Figure 19. Radiopaque marker (BB) placed on the surface of the breast to identify the exact location of a palpable mass. A, Craniocaudal view. The BB is placed on the superior surface of the breast directly over the palpable mass (arrow). 6,Mediolateral oblique view. The BB is now placed on the medial surface of the breast so it will be as close as possible to the palpable mass (arrow) on the mediolateral oblique view.
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Figure 20. Tangential view used to depict palpable mass not visible on routine mammography views. A, Mediolateral oblique view with radiopaque metallic marker (66)directly over the palpable mass fails to show an abnormality within the overlying dense fibroglandular tissue. B, View tangential to the palpable mass (arrow) casts it over subcutaneous fat, allowing it to be seen. The mass is oval and circumscribed. C,Ultrasonography directly over the palpable mass shows an oval, circumscribed mass with width greater than anterior-posterior diameter. Fine needle aspiration biopsy showed fibroadenoma, concordant with imaging findings. The patient elected not TO have the small mass excised and it has been stable for 10 years.
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biopsy just adds cost to the work-up without contributing to management decisions. In the case of a mammographically or ultrasonographically benign-appearing mass, however, the patient and her physician may defer open biopsy if a needle biopsy confirms a benign diagnosis. An example is a circumscribed, oval mass that proves to be a fibroadenoma at needle biopsy. In this situation, the needle biopsy is a reasonable procedure. If the mass is ill-defined or has suspicious features on ultrasonography, a tissue diagnosis is mandatory (Fig. 21). Then, the value of a needle biopsy has to be questioned. Oval, Round, or Lobular Palpable Mass with Circumscribed and Partially Obscured Margins Additional views and spot compression magnification views can be performed to evaluate the margins better. Again, ultrasonography is performed to rule out a simple cyst. If the work-up reveals an irregular shape or ill-defined margins, excision of the mass is indicated (Fig. 22). Irregular Mass with Ill-Defined or Spiculated Margins Because the mass is palpable and likely malignant, the value of a needle biopsy depends on the management protocol of the surgeon. In a one-step procedure, open biopsy and frozen section are followed immediately by the appropriate surgical treatment.31 In a two-step procedure, the biopsy is performed first, followed by definitive surgery at a later date. In the latter situation, a preoperative core needle biopsy of a suspected carcinoma can provide information about histologic type, invasion, tumor grade, and hormone receptor status that could affect overall management. Imaging-guided core needle biopsy or preoperative needle localization is appropriate if the mass is difficult to palpate but clearly visualized on imaging. PALPABLE MASSES IN WOMEN LESS THAN 30 YEARS OF AGE The recommended work-up of a palpable breast mass is modified for women under 30 years of age because of the lower sensitivity of mammography (Fig. 23). There is consider-
Figure 21. Palpable mass with vague asymmetric density on mammography and suspicious mass on ultrasonography. A, Mediolateral oblique mammogram shows only an asymmetric density (arrow) at the location of the palpable mass, identified by the radiopaque marker (BB). B, Ultrasonography directly over the palpable mass (arrows) shows an irregular shape, ill-defined margins and hypoechoic interior. Ultrasound-guidedcore needle biopsy revealed invasive ductal carcinoma, not otherwise specified type.
able documentation that mammography is less effective in younger women.6 The lower sensitivity of mammography in younger women is caused by the greater likelihood of dense breast tissue c o m p ~ s i t i o n .Approxi~~ mately 30% of women under 35, however, have a primarily fatty breast tissue composition. In addition, the incidence of breast carcinoma is lower in women under 40 years of age. For these reasons, mammography screening is not recommended in this age group unless the woman is at high risk for breast carcinoma. Nonetheless, breast carcinomas do occur in this age group and a complete workup of palpable masses should be done. In
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Figure 22. Palpable mass with ill-defined or spiculated margins on mammography. A, Mediolateral oblique mammogram shows a round mass with ill-defined and spiculated margins at the location of a palpable mass identified by the radiopaque marker (BB). B, Craniocaudal mammogram confirms that the suspicious mass (arrow) matches the palpable abnormality. An asymmetric density (arrowhead) medial to the mass could not be reproduced on other projections and was determined to be overlapping fibroglandular tissue. Excision of the mass revealed invasive ductal carcinoma.
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h Sonography
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Figure 23. Algorithm for evaluation of a palpable mass in a woman 30 years of age or younger.
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Figure 24. Palpable mass in a 28-year-old woman. Ultrasonography was the initial imaging examination. A, Ultrasonography of the palpable abnormality reveals a mass with irregular shape, ill-defined margins and low level, heterogeneous internal echoes. Craniocaudal (B) and mediolateral oblique (C) mammograms were then performed with a radiopaque marker (BB) placed over the palpable mass and adjusted for each view. The mammograms showed an ill-defined mass (arrow) that matched the site of the palpable abnormality. No other suspicious findings were identified. Biopsy revealed infiltrating ductal carcinoma.
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women under the age of 30, ultrasonography is the preferred initial imaging modality for the evaluation of a palpable mass.', If ultrasonography identifies a suspicious abnormality/ mammography should be performed to identify possible multifocal lesions or an intraductal component of an invasive tumor (Fig. 24). As in any age group, protocols should be tailored to the individual clinical problem. References 1. American College of Radiology: Appropriateness Criteria, vol2. Reston, VA, American College of Radiology, 1996 2. American College of Radiology: Breast Imaging Reporting and Data System (BI-RADS), ed 3. Reston, VA, American College of Radiology, 1998 3. Bassett LW, Gold RH, Cove HC: Mammographic spectrum of traumatic fat necrosis: The fallibility of "pathognomonic" signs of carcinoma. AJR Am J Roentgenol 130:119-122, 1987 4. Bassett LW, Hendrick RE, Bassford TL, et al: Quality Determinants of Mammography. Clinical Practice Guideline, No. 13. AHCPR Publication No. 95-0632. Rockville, MD, Agency for Health Care Policy and Research, Public Health Service, US Department of Health and Human Services, 1994 5. Bassett LW, Ysrael M, Gold RH, et al: Usefulness of mammography and sonography in women less than 35 years of age. Radiology 180:831-835, 1991 6. Bennett IC, Freitas R Jr, Fentiman IS: Diagnosis of breast cancer in young women. Aust N Z J Surg 61:284-289, 1991 7. Berkowitz JE, Gatewood MB, Gayler BW: Equivocal mammographic findings: Evaluation with spot compression. Radiology 171:369-371, 1989 8. Ciatto S, Cariaggi P, Bularesi P: The value of routine cytologic examination of breast cyst fluids. Acta Cyto1 31:301-304, 1987 9. Cole-Beuglet C, Soriano RZ, Kurtz AB, et al: Fibroadenoma of the breast: Sonomammography correlated with pathology in 122 patients. AJR Am J Roentgenol 140:369-375, 1983 10. Crothers JG, Butler NF, Fortt RW, et al: Fibroadenolipoma of the breast. Br J Radiol 48:191-202, 1985 11. DOrsi CJ, Kopans DB: Mammographic feature analysis. Semin Roentgenol 28:204-230, 1993 12. Edeiken S: Mammography in the symptomatic woman. Cancer 63:1412-1414, 1989 13. Evans WP: Breast masses: Appropriate evaluation. Radiol Clin North Am 33:1085-1108, 1995 14. Feig SA: Importance of supplementary mammographic views to diagnostfp accuracy.-AJR Am J Roentgenol 151:4041, 1988 15. Fomage BD, Coan JD, David CL: Ultrasound-guided needle biopsy of the breast and other interventional procedures. Radiol Clin North Am 30:167-185, 1992 16. Fornage BD, Lorigan JG, Andry E: Fibroadenoma of the breast: Sonographic appearance. Radiology 172:671-675, 1989 17. Gold RH, Montgomery CK, Rambo ON: Significance of margination of benign and malignant infiltrative mammary lesions: Roentgenologic-pathologic correlation. AJR Am J Roentgenol 118:881-894, 1973
18. Hall FM: Statistics, opinions and controversies among expert mammographers. Breast Dis 6:173, 1993 19. Hillman BJ: New imaging technology and cost containment. AJR Am J Roentgenol 162503-506, 1994 20. Hilton SV, Leopold GR, Olson LK, et al: Real-time breast sonography: Application in 300 consecutive patients. AJR Am J Roentgenol 147:479436, 1986 21. Holland R, Connolly JL, Gelman R, et al: The presence of an extensive intraductal component following a limited resection correlates with prominent residual disease in the remainder of the breast. J Clin Oncol 8:113-118, 1990 22. Homer MJ: Proper placement of a metallic marker on an area of concern in the breast. AJR Am J Roentgenol 16739S391, 1996 23. Jackson VP, Dines KA, Bassett LW, et al: Diagnostic importance of radiographic density of noncalcified breast masses: Analysis of 91 lesions. AJR Am J Roentgenol 15725-28, 1991 24. Kerlikowske K, Grady D, Barclay J, et al: Effect of age, breast density, and family history on the sensitivity of first screening mammography. JAMA 2673338, 1996 25. Kopans DB, Meyer JE, Cohen AM, et al: Palpable breast masses: The importance of preoperative mammography. JAMA 246:2819-1823, 1981 26. Love SM, McGuigan KA, Chap L: The Revlon/UCLA Breast Center Practice Guidelines for the Treatment of Breast Disease. The Cancer Journal 22-15, 1996 27. Mann BD, Giuliano AE, Bassett LW, et al: Delayed diagnosis of breast cancer as a result of normal mammograms. Arch Surg 118:23-24, 1983 28. Parker SH, Jobe WE, Dennis MA, et al: US-guided automated large core breast biopsy. Radiology 187507-511, 1993 29. Rahbar G, Sie AC, Hansen GC, et a1 Ultrasonographic differentiation of benign vs. malignant solid breast masses. Radiology 213:889-894, 1999 30. Rubin E: Six-month follow-up: An alternative view. Radiology 213:15-18, 1999 31. Scanlon EF: The case for and against two-step procedures for the surgical treatment of breast cancer. Cancer 53:677-680, 1984 32. Sickles EA: Efficacy of spot compression-magnification and tangential views in mammographic evaluation of palpable breast masses. Radiology 185:87-90, 1992 33. Sickles E A Nonpalpable, circumscribed, noncalcified solid breast masses: Likelihood of malignancy based on lesion size and age of patient. Radiology 192:439442, 1994 34. Sickles EA: Periodic mammographic follow-up of probably benign lesions: Results in 3,184 consecutive cases. Radiology 179:463-468, 1991 35. Sickles E A Probably benign breast lesions: When should follow-up be recommended and what is the optimal follow-up protocol? Radiology 213:ll-14, 1999 36. Skaane P, Engedal K Analysis of sonographic features in the differentiation of fibroadenoma and invasive ductal carcinoma. AJR Am J Roentgenol 170:109114, 1998 37. So0 MS, Williford ME, Walsh R, et al: Papillary carcinoma of the breast: Imaging findings. AJR Am J Roentzenol 164321-326. 1995 38. Stavr; AT, Thickman D, Rapp CL, et al: Solid breast nodules: Use of sonography to distinguish between
IMAGING OF BREAST MASSES benign and malignant lesions. Radiology 196:123134, 1995 39. Sunshine JH, McNeil BJ: Rapid method for rigorous assessment of radiologic imaging technologies. Radiology 202:549-557, 1997 40. Svane G, Franzen S: Radiologic appearance of nonpalpable intramammary lymph nodes. Acta Radio1 34:577-580, 1993
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41. Woolf SH: AHCPR Interim Manual for Clinical Practice Guideline Development. No. 91-0018. Rockville, MD, Agency for Health Care Policy and Research, US Department of Health and Human Services, 1991 42. Yang WT, 5uen M, Metreweli C: Sonographic features of benign papillary neoplasms of the breast: Review of 22 patients. J Ultrasound Med 16:161-168,1997 Address reprint requests to Lawrence W. Bassett, MD 200 UCLA Medical Plaza, Rm 165-47 Box 956952 Los Angeles, CA 90095-6952
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