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MRI findings of primary breast lymphoma in two cases
Clinical Imaging 39 (2015) 682–684
Contents lists available at ScienceDirect
Clinical Imaging journal homepage: http://www.clinicalimaging.org
F-18 FDG PET/MRI findings of primary breast lymphoma in two cases FDG PET/MRI findings of primary breast lymphoma Eun Jung Kong ⁎, Ihn Ho Cho Department of Nuclear Medicine, Yeungnam University, College of Medicine, Daegu, Republic of Korea
a r t i c l e
i n f o
Article history: Received 29 December 2014 Accepted 21 January 2015 Keywords: Breast lymphoma PET/MRI MRI FDG
a b s t r a c t We present the integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) findings of diffuse large B-cell lymphoma involving the breast in two women. They were admitted with palpable breast masses. PET/MRI revealed high 18F-fluorodeoxyglucose (FDG) uptake in multinodular enhancing masses without other FDG-avid foci. Diffusion-weighted imaging showed restricted water diffusion and dynamic contrast MRI showed rapid increase and washout kinetics. High FDG accumulation in tumor is related to washout kinetics. We present the usefulness of integrated PET/MRI for lesion characterization and total body staging in breast lymphoma. © 2015 Elsevier Inc. All rights reserved.
1. Introduction Non-Hodgkin’s lymphoma (NHL) of the breast is an uncommon cancer that occurs either as primary extranodal disease or secondary to a systemic disease. Primary breast lymphoma (PBL) has been reported to account for 0.04–0.5% of all breast malignancies and less than 1% of all patients with NHL [1,2]; this rarity may be related to the small amount of lymphoid tissue in the breast. Most breast lymphomas are classified as diffuse large B-cell lymphoma (DLBCL) or as mucosaassociated lymphoid tissue lymphoma. F-18 Fluorodeoxyglucose (FDG) positron emission tomography (PET) has been useful for the diagnosis, staging, and restaging of lymphoma with accuracies ranging from 80% to 90% [3,4]. Dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI) is currently the most sensitive detection technique for breast cancer. Furthermore, diffusion-weighted MRI [diffusion-weighted imaging (DWI)] probes the microscopic motions of water molecules, and the measured apparent diffusion coefficients (ADCs) are sensitive to cell density, membrane integrity, and tissue microstructure. Recently, an integrated PET/magnetic resonance (MR) system became available, and we used it to examine two patients with PBL. Here, we describe the imaging findings obtained. 2. Case 1 In July 2012, a 35-year-old woman presented with a right breast lump of 3 weeks duration. She had no fever and no evidence of weight loss or night sweats. A core needle biopsy revealed a DLBCL. The patient ⁎ Corresponding author. 170 Hyenchoong Ro, Nam-gu, Daegu, Republic of Korea, 705717. Tel.: +82-53-620-3076; fax: +82-53-620-3079. E-mail address: [email protected] (E.J. Kong). http://dx.doi.org/10.1016/j.clinimag.2015.01.015 0899-7071/© 2015 Elsevier Inc. All rights reserved.
was referred for DLBCL characterization and staging by FDG PET/MR. PET/MR scan was performed using an integrated system (Biograph mMR; Siemens Healthcare, Erlangen, Germany). Initially, a supine whole-body PET/MR scan was performed and, then, PET/MR mammography (PMM) was performed in the prone position using a dedicated breast coil. The PMM protocol comprised a breast PET scan for 8 min with simultaneous breast MRI. The PMM revealed three intensely FDG-avid masses—sized 4.5 cm, 2 cm, and 1.3 cm—in the right breast with SUVmax of 17.07, 6.28, and 4.65, respectively (Fig. 1). There was no evidence of other organ involvement. All three tumors had similar appearances on MR images. The following description focuses on the largest mass. The well-defined oval mass was homogeneously isointense on T1w images and slightly hypointense with internal linear structure on fat-saturated (fs) T2w images. DWI revealed relatively homogeneous signals of high intensity with an ADC value of 0.711×10−3 mm 2/s. DCE MRI demonstrated intense and heterogeneous enhancement with rapid increase (peak enhancement value: 106%) and washout kinetics. Early images showed penetrating vessels in the mass, and delayed images showed peripheral enhancement with a multinodular appearance and intratumoral septal enhancement [5]. The high FDG avidity portion of the tumor showed rapid increase and washout kinetics; however, the low FDG avidity portion showed slow initial enhancement or plateau kinetics. DWI showed tumor margins similar to those of PET but presented a low ADC relatively uniform. The patient underwent sixth cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) chemotherapy and radiotherapy (4000 cGy). FDG PET/computed tomography (CT) scans after 3 cycles of chemotherapy and 16 months after the completion of therapy showed reduced FDG uptake and resolution of all three lesions, respectively. However, routine follow-up PET/CT discovered recurred DLBCL at 20 months after the therapy, which was confirmed by biopsy.
E.J. Kong, I.H. Cho / Clinical Imaging 39 (2015) 682–684
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Fig. 1. (Case 1) A 35-year-old woman with three DLBCL masses in her right breast—sized 4.5 cm, 2 cm, and 1.3 cm. (A) FDG PET MIP image showing hypermetabolic breast masses without other organ involvement. (B) DCE MR image showing two hypervascular masses. The larger mass shows a heterogenous distribution with rapid initial enhancement and washout kinetics. (C and D) FDG PET/MR and PET images show two hypermetabolic oval masses. The high FDG-avid portions of mass show rapid increase and washout kinetics, whereas low FDG uptake portions show slow initial enhancement or plateau kinetics. (E) DCE MRI MIP showing well-defined oval masses with penetrating vessels. (F) DCE image showing a multinodular appearance and septal enhancement. (G and H) ADC map and DWI reflect high cellularity of the tumor. DWI and PET depict similar tumor margins, but DWI presented uniformly intense low ADC lesion. (I) DCE image showing penetrating vessels.
3. Case 2 In October 2013, a 52-year-old woman with no significant previous medical history presented with a right breast mass of 3 weeks duration. A biopsy revealed DLBCL, and the patient was referred for an FDG PET/ MR scan. The PMM revealed an irregularly shaped hypermetabolic mass consisting of aggregation of multiple oval masses, the longest diameter was 9.2 cm and its SUVmax was 19.3 (Fig. 2). The mass was homogeneously isointense on T1w images, but fs T2w images showed heterogeneous hyperintensity mass with peritumoral edema. DWI revealed high signal intensity with heterogeneous distribution with an ADC value of 1.034×10 −3 mm2/s. DCE MRI demonstrated intense and heterogeneous enhancement with rapid increase (peak enhancement value: 174%) and washout kinetics. Early images showed vessels penetrating the mass and delayed images showed an intratumoral multinodular appearance [5]. High FDG avidity region of the tumor coincided with rapid initial enhancement with washout kinetics. The tumor margin was similar on DWI and PET images, but tumor texture on DWI showed relatively uniform. There was no evidence of other organ involvement. The patient underwent sixth cycles of R-CHOP chemotherapy and radiotherapy (2880 cGy). A repeat FDG PET/CT scan after 3 cycles of chemotherapy showed faint FDG uptake and a reduced mass size. Repeat FDG PET/CT scans at 7 months after the completion of chemotherapy showed complete resolution. 4. Discussion Although imaging features are nonspecific and cannot make a diagnosis in isolation, imaging findings are important for establishing disease extent and for planning therapy. Here, we describe the two patients with PBL that were subjected to FDG PET/MRI. As previously reported, both patients presented with palpable breast masses in the fourth and sixth decades of life [6,7]. Unilateral involvement with right-side predominance was observed, which agree with previous study [6]. FDG PET/CT has become the imaging modality of choice for the diagnosis, staging, and follow-up of patients with extranodal involvement in Hodgkin disease and in most cases of NHL [8]. Breast lymphomatous involvement has strong FDG uptake: diffuse uptake, ring-shaped uptake,
or intense focal uptake is possible [8]. However, the CT component of PET/CT inadequately describes anatomical abnormalities of breast lesions, and thus, hybrid PET/MR has potentially greater diagnostic value because of the superior features of MRI in increased soft tissue contrast and ability to provide functional information. Although MRI has become an integral component of breast imaging practice, few reports have been released on the appearance of PBL by MRI due its rarity [6,7,9]. In a previous report, PBL was found to be hypointense or isointense mass on T1w images and hyperintense on T2w images [7,8]. The characteristic features of more common breast carcinomas, such as calcifications, spiculations, or architectural distortions, are not observed in lymphoma [10,11]. Tumors show restricted water diffusion with a homogenous or heterogenous distribution on DWI, which are not specific for lymphoma as they are characteristic of malignancies [6]. Regarding contrast enhancement, intense global heterogeneous enhancement was observed with initial rapid increase and washout-type kinetics, which agrees with our findings [6]. Matsubayashi et al. [5] described a multinodular appearance and intratumoral septal enhancement and linear structures on fs T2w images, which were similar to those observed in our cases. Because of the rarity of breast lymphoma, it is not usually considered in the differential diagnosis of breast tumors. However, well-enhancing high FDG avidity tumor with a circumscribed margin containing penetrating vessels and a multinodular appearance with septal enhancement are useful diagnostic clues of PBL. In addition, high FDG avidity corresponds with rapid increase and washout kinetics, whereas low FDG avidity corresponds with slow initial enhancement or persistent kinetics by DCE MRI. DWI and PET images showed similar tumor margins, but presented low ADC lesion showed a relatively uniform. These imaging features of PBL are not pathognomonic, but familiarity with these findings may alert physicians to the possibility of PBL during the differential diagnosis. 5. Conclusion FDG PET/MR has advantages over other imaging modalities because of the whole-body staging allowed by PET and the accurate determination of disease extent by MRI. Furthermore, the use of multiparametric approach offers the advantages of PET in combination with the superb functional MR and might play a key role in future breast mass
684
E.J. Kong, I.H. Cho / Clinical Imaging 39 (2015) 682–684
Fig. 2. (Case 2) A 52-year-old woman with a DLBCL in her right breast. (A) FDG PET MIP image showing a hypermetabolic breast mass without other organ involvement. (B) DCE MRI showing a hypervascular mass with heterogenous enhancement. Masses show rapid increase and washout kinetics. (C and D) FDG PET/MR and PET images showing a hypermetabolic irregular mass. The high FDG-avid portions of the tumor show rapid initial enhancement and washout kinetics, whereas the low FDG uptake portions show slow initial enhancement or plateau kinetics. (E) DCE image showing a multinodular appearance in the mass. (F) MIP DCE MR image showing multinodular masses with penetrating vessels. (G and H) ADC map and DWI shows high cellularity of the tumor. DWI and PET depict similar tumor margins, but DWI presented uniformly intense low ADC lesion.
evaluations. This report describes examples of the win-win use of PET and MR to identify PBL. Eun Jung Kong and Ihn Ho Cho have no potential conflict of interest to declare. References [1] Domchek SM, Hecht JL, Fleming MD, Pinkus GS, Canellos GP. Lymphomas of the breast: primary and secondary involvement. Cancer 2002;94:6–13. [2] Jeanneret-Sozzi W, Taghian A, Epelbaum R, Poortmans P, Zwahlen D, Amsler B, et al. Primary breast lymphoma: patient profile, outcome and prognostic factors. A multicentre Rare Cancer Network study. BMC Cancer 2008;8:86. [3] Kumar R, Xiu Y, Dhurairaj T, Yu JQ, Alavi A, Zhuang H. F-18 FDG positron emission tomography in non-Hodgkin lymphoma of the breast. Clin Nucl Med 2005;30: 246–8.
[4] Avril NE, Weber WA. Monitoring response to treatment in patients utilizing PET. Radiol Clin N Am 2005;43:189–204. [5] Matsubayashi RN, Inoue Y, Okamura S, Momosaki S, Nakazono T, Muranaka T. MR imaging of malignant primary breast lymphoma: including diffusion-weighted imaging, histologic features, and a literature review. Jpn J Radiol 2013;31:668–76. [6] Yang WT, Lane DL, Le-Petross HT, Abruzzo LV, Macapinlac HA. Breast lymphoma: imaging findings of 32 tumors in 27 patients. Radiology 2007;245:692–702. [7] Liu K, Xie P, Peng W, Zhou Z. The features of breast lymphoma on MRI. Br J Radiol 2013;86:20130220. [8] Paes FM, Kalkanis DG, Sideras PA, Serafini AN. FDG PET/CT of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease. Radiographics 2010;30:269–91. [9] Rizzo S, Preda L, Villa G, Brambilla S, Pruneri G, Alietti A, et al. Magnetic resonance imaging of primary breast lymphoma. Radiol Med 2009;114:915–24. [10] Lyou CY, Yang SK, Choe DH, Lee BH, Kim KH. Mammographic and sonographic findings of primary breast lymphoma. Clin Imaging 2007;31:234–8. [11] Irshad A, Ackerman SJ, Pope TL, Moses CK, Rumboldt T, Panzegrau B. Rare breast lesions: correlation of imaging and histologic features with WHO classification. Radiographics 2008;28:1399–414.
Contents lists available at ScienceDirect
Clinical Imaging journal homepage: http://www.clinicalimaging.org
F-18 FDG PET/MRI findings of primary breast lymphoma in two cases FDG PET/MRI findings of primary breast lymphoma Eun Jung Kong ⁎, Ihn Ho Cho Department of Nuclear Medicine, Yeungnam University, College of Medicine, Daegu, Republic of Korea
a r t i c l e
i n f o
Article history: Received 29 December 2014 Accepted 21 January 2015 Keywords: Breast lymphoma PET/MRI MRI FDG
a b s t r a c t We present the integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) findings of diffuse large B-cell lymphoma involving the breast in two women. They were admitted with palpable breast masses. PET/MRI revealed high 18F-fluorodeoxyglucose (FDG) uptake in multinodular enhancing masses without other FDG-avid foci. Diffusion-weighted imaging showed restricted water diffusion and dynamic contrast MRI showed rapid increase and washout kinetics. High FDG accumulation in tumor is related to washout kinetics. We present the usefulness of integrated PET/MRI for lesion characterization and total body staging in breast lymphoma. © 2015 Elsevier Inc. All rights reserved.
1. Introduction Non-Hodgkin’s lymphoma (NHL) of the breast is an uncommon cancer that occurs either as primary extranodal disease or secondary to a systemic disease. Primary breast lymphoma (PBL) has been reported to account for 0.04–0.5% of all breast malignancies and less than 1% of all patients with NHL [1,2]; this rarity may be related to the small amount of lymphoid tissue in the breast. Most breast lymphomas are classified as diffuse large B-cell lymphoma (DLBCL) or as mucosaassociated lymphoid tissue lymphoma. F-18 Fluorodeoxyglucose (FDG) positron emission tomography (PET) has been useful for the diagnosis, staging, and restaging of lymphoma with accuracies ranging from 80% to 90% [3,4]. Dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI) is currently the most sensitive detection technique for breast cancer. Furthermore, diffusion-weighted MRI [diffusion-weighted imaging (DWI)] probes the microscopic motions of water molecules, and the measured apparent diffusion coefficients (ADCs) are sensitive to cell density, membrane integrity, and tissue microstructure. Recently, an integrated PET/magnetic resonance (MR) system became available, and we used it to examine two patients with PBL. Here, we describe the imaging findings obtained. 2. Case 1 In July 2012, a 35-year-old woman presented with a right breast lump of 3 weeks duration. She had no fever and no evidence of weight loss or night sweats. A core needle biopsy revealed a DLBCL. The patient ⁎ Corresponding author. 170 Hyenchoong Ro, Nam-gu, Daegu, Republic of Korea, 705717. Tel.: +82-53-620-3076; fax: +82-53-620-3079. E-mail address: [email protected] (E.J. Kong). http://dx.doi.org/10.1016/j.clinimag.2015.01.015 0899-7071/© 2015 Elsevier Inc. All rights reserved.
was referred for DLBCL characterization and staging by FDG PET/MR. PET/MR scan was performed using an integrated system (Biograph mMR; Siemens Healthcare, Erlangen, Germany). Initially, a supine whole-body PET/MR scan was performed and, then, PET/MR mammography (PMM) was performed in the prone position using a dedicated breast coil. The PMM protocol comprised a breast PET scan for 8 min with simultaneous breast MRI. The PMM revealed three intensely FDG-avid masses—sized 4.5 cm, 2 cm, and 1.3 cm—in the right breast with SUVmax of 17.07, 6.28, and 4.65, respectively (Fig. 1). There was no evidence of other organ involvement. All three tumors had similar appearances on MR images. The following description focuses on the largest mass. The well-defined oval mass was homogeneously isointense on T1w images and slightly hypointense with internal linear structure on fat-saturated (fs) T2w images. DWI revealed relatively homogeneous signals of high intensity with an ADC value of 0.711×10−3 mm 2/s. DCE MRI demonstrated intense and heterogeneous enhancement with rapid increase (peak enhancement value: 106%) and washout kinetics. Early images showed penetrating vessels in the mass, and delayed images showed peripheral enhancement with a multinodular appearance and intratumoral septal enhancement [5]. The high FDG avidity portion of the tumor showed rapid increase and washout kinetics; however, the low FDG avidity portion showed slow initial enhancement or plateau kinetics. DWI showed tumor margins similar to those of PET but presented a low ADC relatively uniform. The patient underwent sixth cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) chemotherapy and radiotherapy (4000 cGy). FDG PET/computed tomography (CT) scans after 3 cycles of chemotherapy and 16 months after the completion of therapy showed reduced FDG uptake and resolution of all three lesions, respectively. However, routine follow-up PET/CT discovered recurred DLBCL at 20 months after the therapy, which was confirmed by biopsy.
E.J. Kong, I.H. Cho / Clinical Imaging 39 (2015) 682–684
683
Fig. 1. (Case 1) A 35-year-old woman with three DLBCL masses in her right breast—sized 4.5 cm, 2 cm, and 1.3 cm. (A) FDG PET MIP image showing hypermetabolic breast masses without other organ involvement. (B) DCE MR image showing two hypervascular masses. The larger mass shows a heterogenous distribution with rapid initial enhancement and washout kinetics. (C and D) FDG PET/MR and PET images show two hypermetabolic oval masses. The high FDG-avid portions of mass show rapid increase and washout kinetics, whereas low FDG uptake portions show slow initial enhancement or plateau kinetics. (E) DCE MRI MIP showing well-defined oval masses with penetrating vessels. (F) DCE image showing a multinodular appearance and septal enhancement. (G and H) ADC map and DWI reflect high cellularity of the tumor. DWI and PET depict similar tumor margins, but DWI presented uniformly intense low ADC lesion. (I) DCE image showing penetrating vessels.
3. Case 2 In October 2013, a 52-year-old woman with no significant previous medical history presented with a right breast mass of 3 weeks duration. A biopsy revealed DLBCL, and the patient was referred for an FDG PET/ MR scan. The PMM revealed an irregularly shaped hypermetabolic mass consisting of aggregation of multiple oval masses, the longest diameter was 9.2 cm and its SUVmax was 19.3 (Fig. 2). The mass was homogeneously isointense on T1w images, but fs T2w images showed heterogeneous hyperintensity mass with peritumoral edema. DWI revealed high signal intensity with heterogeneous distribution with an ADC value of 1.034×10 −3 mm2/s. DCE MRI demonstrated intense and heterogeneous enhancement with rapid increase (peak enhancement value: 174%) and washout kinetics. Early images showed vessels penetrating the mass and delayed images showed an intratumoral multinodular appearance [5]. High FDG avidity region of the tumor coincided with rapid initial enhancement with washout kinetics. The tumor margin was similar on DWI and PET images, but tumor texture on DWI showed relatively uniform. There was no evidence of other organ involvement. The patient underwent sixth cycles of R-CHOP chemotherapy and radiotherapy (2880 cGy). A repeat FDG PET/CT scan after 3 cycles of chemotherapy showed faint FDG uptake and a reduced mass size. Repeat FDG PET/CT scans at 7 months after the completion of chemotherapy showed complete resolution. 4. Discussion Although imaging features are nonspecific and cannot make a diagnosis in isolation, imaging findings are important for establishing disease extent and for planning therapy. Here, we describe the two patients with PBL that were subjected to FDG PET/MRI. As previously reported, both patients presented with palpable breast masses in the fourth and sixth decades of life [6,7]. Unilateral involvement with right-side predominance was observed, which agree with previous study [6]. FDG PET/CT has become the imaging modality of choice for the diagnosis, staging, and follow-up of patients with extranodal involvement in Hodgkin disease and in most cases of NHL [8]. Breast lymphomatous involvement has strong FDG uptake: diffuse uptake, ring-shaped uptake,
or intense focal uptake is possible [8]. However, the CT component of PET/CT inadequately describes anatomical abnormalities of breast lesions, and thus, hybrid PET/MR has potentially greater diagnostic value because of the superior features of MRI in increased soft tissue contrast and ability to provide functional information. Although MRI has become an integral component of breast imaging practice, few reports have been released on the appearance of PBL by MRI due its rarity [6,7,9]. In a previous report, PBL was found to be hypointense or isointense mass on T1w images and hyperintense on T2w images [7,8]. The characteristic features of more common breast carcinomas, such as calcifications, spiculations, or architectural distortions, are not observed in lymphoma [10,11]. Tumors show restricted water diffusion with a homogenous or heterogenous distribution on DWI, which are not specific for lymphoma as they are characteristic of malignancies [6]. Regarding contrast enhancement, intense global heterogeneous enhancement was observed with initial rapid increase and washout-type kinetics, which agrees with our findings [6]. Matsubayashi et al. [5] described a multinodular appearance and intratumoral septal enhancement and linear structures on fs T2w images, which were similar to those observed in our cases. Because of the rarity of breast lymphoma, it is not usually considered in the differential diagnosis of breast tumors. However, well-enhancing high FDG avidity tumor with a circumscribed margin containing penetrating vessels and a multinodular appearance with septal enhancement are useful diagnostic clues of PBL. In addition, high FDG avidity corresponds with rapid increase and washout kinetics, whereas low FDG avidity corresponds with slow initial enhancement or persistent kinetics by DCE MRI. DWI and PET images showed similar tumor margins, but presented low ADC lesion showed a relatively uniform. These imaging features of PBL are not pathognomonic, but familiarity with these findings may alert physicians to the possibility of PBL during the differential diagnosis. 5. Conclusion FDG PET/MR has advantages over other imaging modalities because of the whole-body staging allowed by PET and the accurate determination of disease extent by MRI. Furthermore, the use of multiparametric approach offers the advantages of PET in combination with the superb functional MR and might play a key role in future breast mass
684
E.J. Kong, I.H. Cho / Clinical Imaging 39 (2015) 682–684
Fig. 2. (Case 2) A 52-year-old woman with a DLBCL in her right breast. (A) FDG PET MIP image showing a hypermetabolic breast mass without other organ involvement. (B) DCE MRI showing a hypervascular mass with heterogenous enhancement. Masses show rapid increase and washout kinetics. (C and D) FDG PET/MR and PET images showing a hypermetabolic irregular mass. The high FDG-avid portions of the tumor show rapid initial enhancement and washout kinetics, whereas the low FDG uptake portions show slow initial enhancement or plateau kinetics. (E) DCE image showing a multinodular appearance in the mass. (F) MIP DCE MR image showing multinodular masses with penetrating vessels. (G and H) ADC map and DWI shows high cellularity of the tumor. DWI and PET depict similar tumor margins, but DWI presented uniformly intense low ADC lesion.
evaluations. This report describes examples of the win-win use of PET and MR to identify PBL. Eun Jung Kong and Ihn Ho Cho have no potential conflict of interest to declare. References [1] Domchek SM, Hecht JL, Fleming MD, Pinkus GS, Canellos GP. Lymphomas of the breast: primary and secondary involvement. Cancer 2002;94:6–13. [2] Jeanneret-Sozzi W, Taghian A, Epelbaum R, Poortmans P, Zwahlen D, Amsler B, et al. Primary breast lymphoma: patient profile, outcome and prognostic factors. A multicentre Rare Cancer Network study. BMC Cancer 2008;8:86. [3] Kumar R, Xiu Y, Dhurairaj T, Yu JQ, Alavi A, Zhuang H. F-18 FDG positron emission tomography in non-Hodgkin lymphoma of the breast. Clin Nucl Med 2005;30: 246–8.
[4] Avril NE, Weber WA. Monitoring response to treatment in patients utilizing PET. Radiol Clin N Am 2005;43:189–204. [5] Matsubayashi RN, Inoue Y, Okamura S, Momosaki S, Nakazono T, Muranaka T. MR imaging of malignant primary breast lymphoma: including diffusion-weighted imaging, histologic features, and a literature review. Jpn J Radiol 2013;31:668–76. [6] Yang WT, Lane DL, Le-Petross HT, Abruzzo LV, Macapinlac HA. Breast lymphoma: imaging findings of 32 tumors in 27 patients. Radiology 2007;245:692–702. [7] Liu K, Xie P, Peng W, Zhou Z. The features of breast lymphoma on MRI. Br J Radiol 2013;86:20130220. [8] Paes FM, Kalkanis DG, Sideras PA, Serafini AN. FDG PET/CT of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease. Radiographics 2010;30:269–91. [9] Rizzo S, Preda L, Villa G, Brambilla S, Pruneri G, Alietti A, et al. Magnetic resonance imaging of primary breast lymphoma. Radiol Med 2009;114:915–24. [10] Lyou CY, Yang SK, Choe DH, Lee BH, Kim KH. Mammographic and sonographic findings of primary breast lymphoma. Clin Imaging 2007;31:234–8. [11] Irshad A, Ackerman SJ, Pope TL, Moses CK, Rumboldt T, Panzegrau B. Rare breast lesions: correlation of imaging and histologic features with WHO classification. Radiographics 2008;28:1399–414.