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Neoplasms of the trachea and main stem bronchi
Neoplasms of the Trachea and Main Stem Bronchi By Benjamin Felson
O M E general remarks that also apply to tracheal tumors have already been made in the in this Seminar. The following comments apply more specifically to neoplasms. The radiographic differential diagnosis between benign and malignant tumors of the trachea may be difficult, j A mass under 2 cm in length is generally benign; most malignant tumors are more than 4 cm in length. Malignant tumors usually have an irregular surface, extend along the tracheal wall, and invade the adjacent mediastinal structures. Benign tumors are often smooth, rounded, and more localized. It should be noted that any tumor of the trachea, benign or malignant, may extend into and even block a main stem bronchus. Since the term polyp is merely a gross morphologic label, it is not considered a separate entity unless its histologic nature is stated. However, a truly pedunculated lesion is almost always benign (Fig. 1). The presence of calcium does not distinguish a benign from a malignant tumor. Chondroma, hamartoma, bronchial adenoma, and hemangioma can calcify, but so can chondrosarcoma. Although you may not agree, I have arbitrarily chosen to include the bronchial adenomas among the benign lesions, chiefly because of their slow growth, good prognosis, and close radiographic resemblance to other tumors that are always benign.
S Letter From the Editor
BENIGN TUMORS Adenomas
The most frequent adenoma of the trachea is the cylindroma, also called adenoid cystic tumor. It has a predilection for the middle third. It accounts for about 40% of tracheal tumors. 2 It is apparently a different tumor from the skin lesion of the same name. It has a predilection for the middle third of the trachea, and grows slowly. It metastasizes late, chiefly to bone and lung. 3'4 Less frequent is the mucoepidermoid adenoma, composed of mucus-secreting and epidermoid cells. 5'6 Although common in the larger bronchi, carcinoid is infrequent in the trachea. It
Seminars in Roentgenology, Vol. XVlll, No. 1 (January), 1983
is rarely associated with the carcinoid syndrome. 7,8 The adenomas tend to invade the tracheal wall and extend into the adjacent mediastinal structures. The nearby lymph nodes may be involved. Distant metastasis occurs late; even then the course is often prolonged, so that a patient with persistent tumor may live for 10 yr or more in a relatively good state of health. Radiographically the adenomas are a l m o s t always rounded, sessile, smooth-surfaced, and sharply demarcated. It is surprising how much of the tracheal lumen can be encroached on before symptoms of obstruction appear (Fig. 2). Blockage of a main stem bronchus may occur from an adenoma arising in the bronchus (Fig. 3) or lower trachea. Mediastinal extension and lymph node metastases may be detected by a variety of methods, the least invasive of which are esophagography, tomography, and CT. Spindle Cell Tumors
Spindle cell tumors of the trachea or main stem bronchus are not so rare, usually presenting as a sharply defined rounded tumor identical to the adenomas. Mediastinal extension is seldom a feature. Neurinomas of various types, including neurofibroma (Fig. 4) and neurilemoma, may occur in the trachea or main bronchus] The lesion may represent a local manifestation of neurofibromatosis or an isolated tumor, it may occur anywhere along the trachea or in either main stem bronchus. lntraluminal tracheal paraganglioma may secrete hormones that can be detected chemically or functionally. 9 ~ Leiomyoma of the trachea, as elsewhere in the body, is a slow growing lesion that arises intramurally, most commonly in the lower third. From the Department of Radiology, University of Cincinnati College of Medicine, Cincinnati, Ohio. Benjamin Felson: Professor of Radiology, University of Cincinnati College of Medicine. Address reprint requests to Benjamin Felson, M.D., Department of Radiology, University Hospital, Cincinnati, Ohio 45267. 9 1983 by Grune & Stratton, Inc. 0270-9 295/83/1801~0006502.00/0
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BENJAMIN FELSON
Fig. 1. Pedunculated epithelial polyp. The tumor, attached to the wall of the right main stem bronchus, has extended into the trachea on this bronchographic spot film (arrowheads). Later in the study it flipped into the right lower lobe bronchus.
Fig. 2. Cylindroma of the trachea w i t h a right upper lobe metastasis. (A) Plain film. The trachea is slightly less lucent just below the level of the clavicles than it is above and below this level. (B) The tomogram shows a smooth, round, sharply marginated mass which seems to fill the entire tracheal lumen. The patient had recent onset of bouts of "asthma.'"
B
Fig. 3. A fascinating case of carcinoid of t h e left main stem bronchus. The patient had had i n t e r m i t t e n t hemoptysis for several years. (A) PA teleo. The entire left lung is collapsed. The right lung has herniated all the w a y to the left lateral chest wall. The left main stem bronchus shows a cut-off. |B) Left lateral teleo. The heart is displaced far posteriorly by t h e herniated right lung. Congenital absence of the left lung was also given consideration. (C) Tomogram. Branches of right pulmonary vessels (arrowheads) extend across the midline into the aerated pulmonary tissue in t h e left lateral thorax. (D) Arteriogram. The injection was made via a catheter in the lower descending thoracic aorta. "Bronchial arteries" emanating from the aorta (lower arrow) anastomose w i t h left pulmonary artery branches. Retrograde f l o w into the left main pulmonary artery (upper arrow) indicates that there is a left lung.
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Fig. 4. Neurofibroma of the trachea. This oblique tomogram shows a sharply outlined Iobular tumor arising from the posterior trachea wall (arrow). The patient had neurofibromastosis.
BENJAMIN FELSON
Pathologically it has a smooth surface and a broad sessile base. It may have an iceberg configuration, a small component projecting into the tracheal lumen with the bulk of the lesion extending into the adjacent mediastinum. '2'~3 Granular cell myoblastoma is a rare benign tumor of the larynx, trachea, or major bronchi, most common in black females 30-50 yr of age. This lesion closely resembles the other spindle cell tumors grossly. It may be sessile or pedunculated. It is characterized histologically by large granular foamy cells in syncytial masses. The tumor usually arises in the cervical trachea and tends to infiltrate adjacent structures, including the esophagus. It may be multiple, and occasionally undergoes malignant degeneration. ~4-~6 Fibroma usually occurs in the cervical segment of the trachea. It is more common in children. It ususally presents as a solitary welldefined sessile tracheal nodule, but may be pedunculated, j7 Fibrous histiocytoma is the name recently applied to a benign or malignant fibrous tumor,
Fig. 5. Leiomyosarcoma of the lower trachea. (A) AP and (B) lateral tomograrns show a well-defined slightly Iobulated lesion (arrows). Benign spindle cell tumors have an identical appearance. (Courtesy of Col, Sherry Brahman, Walter Reed Army Hospital.)
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most commonly arising in bone but occasionally primary in the thorax or elsewhere. Selection of this name is unfortunate, since it has preempted a term formerly applied to a different tumor of the respiratory tract, also known as xanthoma or pseudotumor, a benign lesion composed of histiocytes and xanthomatous and fibrous tissue. Both types of histiocytoma have been reported in the trachea. !8 Lipoma rarely occurs in the trachea or main stem bronchus. It may be mucosal or mural, round or lobulated, pedunculated or sessile. Because of its small size and location, its fat content cannot be recognized by any of the current radiographic modalities. 7 Malignant spindle cell tumors may closely resemble their benign counterpart, both histologically and radiographically (Fig. 5). Differentiation seldom can be made unless metastases are demonstrated. When the microscopic appearance is clearly malignant, the tumor is grossly and radiographically irregular and resembles tracheal carcinoma. 7J9
Angiomatous Tumors Hemangioma of the trachea is usually an isolated lesion but may be associated with hemangiomas elsewhere in the body. It is the
Fig. 6. Laryngotracheal hemangioma in a child. The Iobulated tumor involves the vocal cords and ventricle and extends into the subglottic region (arrowheads).
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commonest tracheal neoplasm in the pediatric age group, and is rare in adults. Most occur in the upper trachea or extend downward from the larynx. In fact, a solitary laryngotracheal lesion in a child is usually a hemangioma. The hemangioma is generally of the cavernous type. Radiographically it appears as a nodular mass (Fig. 6), occasionally containing phleboliths. As with hemangiomas elsewhere, spontaneous regression may o c c u r . 2~ Hemangioendothelioma is exceedingly rare and has no particular identifying radiographic features. 22 These angiomatous lesions generally show a high degree of vascularity on angiography, sometimes enabling the diagnosis to be suggested. Cartilaginous Tumors 23 Surprisingly only a few solitary cartilanginous tumors of the trachea have been reported. Chondroma is a well-circumscribed, hard smooth-surfaced tumor attached to a cartilaginous ring and covered by normal epithelium. It may involve any level of the trachea. Radiographically it is seen as an intratracheal nodule measuring from a few mm to 3 cm in diameter. The tracheal wall doesn't usually appear thickened, and extratracheai extension is uncommon. In most cases, typical cartilaginous calcification is seen within the tumor. A chondroma of the distal trachea may extend into a main stem bronchus, causing collapse or air trapping. Much that has been said about chondroma applies also to chondrosarcoma, a slow growing tumor that spreads into the mediastinum and metastasizes widely late in its course. As with spindle cell tumors, histologic criteria for malignancy may be lacking. Hamartoma is usually a chondromatous tumor, but contains other components in addition to the cartilage, such as fat, lymphoid tissue, or epithelial elements. Benign mixed tumor of the trachea is also said to contain cartilage and other elements that resemble salivary tissue. 24 Why it is considered different from hamartoma escapes me. In fact, I'm not even sure that the hamartoma is different from the chondroma. Certainly they both contain cartilage and grow at about the same rate. Obviously we are at the mercy of the pathologist in distinguishing among chondroma,
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hamartoma, and mixed tumor, in the trachea as in the lung.
Papillomatosis Papillomatosis is a common disease of children, but has also been occasionally reported in adults.25 27 The condition, of uncertain cause, presents with many small warts in the larynx and sometimes in the upper trachea. Verruca on the hands have been reported in some children. The papillomas have been attributed to viral infection, although no virus has ever been isolated. The disease is a source of misery for the afflicted child, requiring repeated local removal of the recurrent nodules, a difficult and painful procedure. Some of the potent new drugs, such as interferon, are said to be effective in controlling the disease, but past experience suggests that a skeptical attitude be maintained. Impairment of speech by the laryngeal nodules is a common problem. The papillomas have a strong tendency to recur after removal and may occasionally seed distally into the tracheobronchial tree, where they appear histologically identical to the laryngeal lesions. The lower respiratory lesions are always preceded by laryngeal papillomas. The bronchial nodules often excavate; the cavities are said to be lined with ciliated or nonciliated columnar epithelium, z6 Recurrences tend to become less frequent as the child grows, 27 seldom occurring after age 16, but remission may not occur at all. 26 Death may occur from recurrent infection or upper airway obstruction. About 10% of the patients die of bronchogenic carcinoma in early adult life, even after total remission of the papillomas. Most of the adult-onset cases have died of the disease. The radiographic findings of tracheobronchial papillomatosis are interesting and often characteristic. Countless lesions may involve the entire length of the trachea (Fig. 7). The nodules in the lower respiratory tract commonly obstruct some of the bronchi, resulting in one or more areas of lobar or segmental collapse or air trapping, or pneumonia (Fig. 8). These may clear spontaneously or after treatment. Individual nodules may grow to several cm in diameter, becoming visible in the lungs on the plain chest film. These slowly increase in number and size with the passage of time. Most of the
Fig. 7. Papillomatosis of the trachea. AP tomogram shows innumerable nodules 3 - 1 0 mm in diameter involving the entire trachea,
lung lesions eventually excavate, resulting in cystic lesions of various sizes, each having a thin or thick smooth wall. 26 The pattern of multiple large smooth thin-walled cavitary lesions in a young patient is essentially diagnostic of papillomatosis (Fig. 9). The cyst walls are thicker than those of bullae but usually thinner and smoother than the cavities of metastatic neoplasm or granuloma (Fig. 10). Unlike cystic bronchiectasis, these lesions seldom contain fluid and do not enlarge on inspiration or fill with contrast medium on bronchography. Histiocytosis X may also show large cysts, but many contain fluid or detritus. I know of no mechanism that explains the development of these large cysts within pulmonary papillomas. A solitary squamous cell papilloma, different from the above variety, has been described in adults. The tumor arises in the mucosa and protrudes into the tracheal lumen (Fig. 1 1). It is composed of squamous epithelium with a core of
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Fig. 8. PapiUomatosis of the tracheobronchial tree w i t h collapse of the right middle lobe and posterior basal segment of the left lower lobe. Note the tracheostomy tube. The lower trachea appears narrowed on the lateral view. Later on, lateral segmental collapse of the left lower lobe appeared.
connective tissue. It may undergo malignant transformation.
Thyroid Tumors Ectopic thyroid tissue, normal histologically, may be found in the tracheal wall, protruding into the lumen. It may undergo goitrous change,
or even become malignant (about 10%). Intratracheal thyroid tumor is not common but does account for 7% of all tracheal tumors. Women are affected three times as often as men. It is more frequent in the endemic goiter areas of Europe, namely Germany and Switzerland. Multiple nodules are rare, but in over two-thirds of
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BENJAMIN FELSON
Fig. 9. Papillomatosis of the lower respiratory tract. (A) Lateral view in 1965 shows multiple nodules, some of which are cavitating (arrows). (B) Lateral view in 1972. The lesions ( a r r o w s and a r r o w h e a d s ) are larger and more numerous. All a r e cavitated. (C) PA teleo, 1972. These multiple thin-walled e m p t y cysts a r e diagnostic of papillomatosis in a youngster.
the cases concurrent goitrous enlargement of the normally placed thyroid gland is noted. There is often a connecting bridge between the two masses through the tracheal wall. The combination of cervical goiter and airway obstruction should suggest intratracheal thyroid tumor. The intratracheal mass is often broad-based and smoothly rounded, usually protruding inward from the left posterolateral subglottic wall. 28'29 Intrathoracic goiter alone may displace or compress the trachea to a remarkable degree,
usually without causing symptoms. Invasion of the trachea by carcinoma in the normally sited thyroid gland is sometimes encountered. MALIGNANT TUMORS Carcinoma
Tracheal carcinoma is an infrequent lesion, accounting for less than 1% of carcinomas of the respiratory tract. 3~Average age of the patients is about 55 yr, and there is male preponderance. In
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Fig. 10. Papillomatosis of the lung in an adult. M a n y small cysts, some w i t h fairly thick walls, are present.
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25% of the patients, the tracheal carcinoma is accompanied, preceded, or followed by a second primary carcinoma in the upper respiratory tract, lung, or digestive tract. Hemoptysis is commonly the first symptom of tracheal carcinoma, but the patient may present with dyspnea, wheezing, or dysphagia. Most of the patients have stridor. Grossly, the tumor may be exophytic, infiltrative, or ulcerated. It may arise from any level in the trachea, and involve only a short segment or
Fig. 11. Solitary squamous papilloma. Lateral tomogram, The large nodule (arrow) almost completely blocks t h e trachea. (Courtesy of Dr. R. T. Rainke of Houston.)
Fig. 12. Small round cell carcinoma of the lower trachea w i t h extension into both main stem bronchi. The carinal and right hilar nodes are involved. (Courtesy of Dr. Robert H. Choplin, Bowman Gray School of Medicine, Winston-Salem, NC.)
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extend along the wall for a considerable distance. The tumor may circumnavigate the trachea like a napkin ring or be confined to one part of the wall. It may involve one or both main stem bronchi (Fig. 12). All histologic varieties are encountered; squamous cell carcinoma is the most common, adenocarcinoma and oat cell carcinoma less frequent. Any grade of microscopic differentiation may occur. Adenocarcinoma is said to grow larger and to penetrate more deeply into the surrounding tissue than the other histologic types. 7'3~ Invasion of the mediastinal soft tissues, spread to lymph nodes, and extension into the esophagus are common. A sinus tract or fistula may develop. Seeding into the lung via the bronchial tree occasionally occurs. Most often the spread is via the blood stream to lung, bone, liver, or brain. Radiographically the tumor is usually irregular (Fig. 13), lobulated (Fig. 14), or annular; most are located above the aortic arch. 32 As stated, the longitudinal and horizontal dimensions of tracheal carcinoma vary considerably. Spread into the mediastinum is often indicated by displacement of adjacent air-bearing pulmonary tissue. The barium esophagram (Fig. 15) and CT (see p. 56) usually give a more vivid demonstration of this spread and help to stage the lesion# ~
Fig. 13. Carcinoma of the trachea. The tracheogram shows an irregular exophytic tumor almost completely blocking the trachea (arrowhead).
BENJAMIN FELSON
Fig. 14. Carcinoma of the trachea. This penetrated grid film shows an elongated tumor extending along the left wall of the trachea,
Other Primary Malignant Tumors Lymphoma of the trachea, primary or as part of a disseminated process, is rare and has no distinguishing gross pathologic or radiographic features except for disproportionate lymph node enlargement. Extension into the trachea from adjacent lymphomatous nodes may occur. 33 As already noted, malignant spindle cell sarcoma usually shows the same radiographic signs as the benign form (Fig. 5), although mediastinal invasion may be more extensive. As stated earlier, chondrosarcoma also resembles its benign counterpart radiographically. It commonly shows considerable flocculent calcification. Any of the sarcomas may show widespread metastasis. Solitary plasmacytoma is a well-documented but rare lesion of the upper respiratory tract. It may arise in the trachea, where it usually presents pathologically and radiographically as a rounded or lobulated mass. It may invade surrounding structures and metastasize to lymph nodes. It occurs late in life and commonly eventuates in multiple myeloma of the skeleton. 34 Other malignant tracheal tumors are ex-
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Fig. 16. Schneiderian polyp of lower third of the trachea. The enlarged carinal nodes w e r e involved by sarcoidl
tremely rare. In carcinosarcoma, the connective tissue elements of a carcinoma are clearly sarcomatous. It appears as a sessile polypoid mass that invades the surrounding tissues. Schneiderian tumor is a malignant lesion that usually arises from the mucous membrane of the nose, but occasionally occurs in the trachea, where it forms a sessile or pedunculated polypoid tumor (Fig. 16). Most primary malignant tumors of the trachea are unresectable because of their spread along the trachea or into the mediastinum, where they often invade the esophagus, lung, or great vessels. CT is especially helpful in demonstrating the extension of these tumors and staging them.
Metastatic Neoplasm Fig. 15. Carcinoma of the trachea invading the esophagus. (A) PA teleo film shows the primary tumor (*), with carinal nodes located more distally. Note the abrupt opacification in the subclavicular segment of the trachea. (B) Barium swallow. The upper part of the esophageal defect was the site of invasion. Most of the defect represented extrinsic pressure from the primary tumor and the carinal nodes.
Metastasis to the trachea, while not a common event, is an interesting one. How and why does a distant maligant tumor implant in the tracheobronchial mucosa? Nobody seems to know for sure, but here is a logical explanation: a tumor microembolus may bypass, traverse, or originate
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BENJAMIN FELSON
Fig. 17. Metastatic neuroblastoma of the trachea. This child had intractable " a s t h m a , " and conventional films (A) and (B) w e r e interpreted as normal on several occasions, although the tracheal lesion is visible (arrowheads), (C) Overexposed AP film shows the tumor more clearly (arrow),
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Fig. 18. Carcinoma of the lung w i t h extension into t h e trachea (arrow). Collapse of the entire left lung. The t u m o r appeared to arise in the left main bronchus and protrude upward into the trachea.
Fig. 19. Carcinoma of t h e esophagus w i t h extension into the trachea (arrowheads), proved at autopsy.
in the lung and deposit in an endartery within the mucosa. Metastasis may be solitary or multiple, sessile or pedunculated. As with bronchial metastasis, the primary site is most often hypernephroma, with melanoma, breast carcinoma, and colon next in line. However, any malignant tumor may on occasion metastasize to the tracheobronchial mucosa (Fig. 17). 35 38
Thyroid carcinoma commonly involves the tracheal wall and may invade its lumen. Severe respiratory obstruction may ensue. Implantation or extension into the upper trachea from laryngeal carcinoma is fairly frequent, especially following tracheostomy or laryngectomy. Bronchogenic carcinoma (Fig. 18) and esophageal carcinoma (Fig. 19) also commonly invade the trachea. A tracheoesophageal fistula
Fig. 20. Inspissated mucus attached to the tracheal wall (arrow). The lesion remained for several months before being coughed up.
Invasion From Extrinsic Tumor
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BENJAMIN FELSON
m a y d e v e l o p s p o n t a n e o u s l y or a f t e r r a d i a t i o n . A t t i m e s it is difficult to d e c i d e if a t r a c h e a l t u m o r is p r i m a r y o r i f it is s e c o n d a r y to a c o n t i g u o u s n e o p l a s m ( c o m p a r e Figs. 15 a n d 19). DIFFERENTIAL DIAGNOSIS
A variety of conditions may simulate neop l a s m o f t h e t r a c h e a . M a n y o f t h e s e a r e disc u s s e d e l s e w h e r e in t h i s S e m i n a r . H o w e v e r , seve r a l lesions d e s e r v e s p e c i a l c o m m e n t .
A g l o b o f i n s p i s s a t e d m u c u s m a y a d h e r e to t h e t r a c h e a l w a l l a n d r e m a i n a t t a c h e d for a c o n s i d e r a b l e p e r i o d o f t i m e ( F i g . 20). 39 R a d i o g r a p h i c a l l y it a p p e a r s as a s m a l l n o d u l e p r o t r u d i n g f r o m t h e mucosal surface into the tracheal lumen. If not r e m o v e d b e c a u s e of s u s p i c i o n o f n e o p l a s m , it will eventually disappear. The mucus may be the r e s u l t o f i m p a i r m e n t o f cilial a c t i o n or a b n o r m a l ity o f t h e m u c u s itself, as in a s p e r g i l l u s s e n s i t i v i ty. A s i m i l a r f i n d i n g m a y o c c u r w i t h a s m a l l a d h e r e n t f o r e i g n b o d y , s u c h as a seed.
REFERENCES
1. Pinet F, Loire R, Maret G, et al: Primary tumours of the trachea. A clinical, radiological and pathologic evaluation of 12 cases. Eur J Radiol 1981 ; 1:88-91 2. Cleveland RH, Nice CM Jr, Ziskind J: Primary adenoid cystic carcinoma (cylindroma) of the trachea. Radiology 1977; 122:597-600 3. Baydur A, Gottlieb LS: Adenoid cystic carcinoma (cylindroma) of the trachea masquerading as asthma. JAMA 1975; 234:829-831 4. Pearson FG, Thompson DW, Weissberg D, et al: Adenoid cystic carcinoma of the trachea. Experience with 16 patients managed by tracheal resection. Ann Thorac Surg 1974; 18:16 29 5. Larson RE, Woolner LB, Payne WS: Mucoepidermoid tumor of the trachea. Report of a case. J Thorac Cardiovasc Surg 1965; 50:131 137 6. Trentini GP, Palmieri B: Mucoepidermoid tumor of the trachea. Chest 1972; 62:336 338 7. Weber AL, Grillo HC: Tracheal tumors: a radiological, clinical, and pathological evaluation of 84 cases. Radiol Clin North Am 1978; 2:227-246 8. Habal MB, Murray JE: Argentaffin adenoma of the trachea. Am J Surg 1973; 125:336-337 9. Horree WA: An unusual primary tumor of the trachea (chemodectoma). Pract Otorhinolaryngol 1963; 25:125-126 10. Zeman MS: Carotid body tumor of the trachea. Ann Otol 1956; 65:96(~962 11. Liew SH, Leong ASY, Tang HMK: Tracheal paraganglioma: a case report with review of the literature. Cancer 1981; 47:1387-1393 12. Foroughi E: Leiomyoma of the trachea. Dis Chest 1962; 42:230-232 13. Sanders JS, Carnes VM: Leiomyoma of the trachea. Report of a case, with a note on the diagnosis of partial tracheal obstruction. N Engl J Med 1961; 264:277-279 14. Canalis RF, Dodson TA, Turkell SB, et al: Granular cell myoblastoma of the cervical trachea. Arch Otolaryngol 1976; 102:176-179 15. Thawley SE, Ogura JH: Granular cell myoblastoma of the trachea. Arch Otolaryngol 1974; 100:393-394 16. Sargent EN, Wilson R, Gordonson J, et al: Granular cell myoblastoma of the trachea: response to radiation therapy. A JR 1972; 114:89-92 17. Miller MAL, Toma GA: Fibroma of the trachea. Br J Dis Chest 1959; 53:177-180
18. Hakimi M, Pai RP, Fine G, et al: Fibrous histiocytoma of the trachea. Chest 1975; 68:367-368 19. Roncoroni A J, Puy RJM, Goldman E, et al: Fibrosarcoma of the trachea with severe tracheal obstruction. Thorax 1973; 28:777-781 20. Hudson HL, McAlister WH: Obstructing tracheal hemangioma in infancy. A JR 1965; 93:428-431 21. Maier HC: Hemangiomas of the subglottic region, trachea and mediastinum in infancy and childhood. Ann Thorac Surg 1967; 3:514-525 22. Flege JB Jr, Valencia G, Zimmerman G: Obstruction of a child's trachea by a polypoid hemangioendothelioma. J Thorac Cardiovasc Surg 1968; 56:144 146 23. Weber AL, Shortsleeve M, Goodman M, et al: Cartilaginous tumors of the larynx and trachea. Rad Clin North Am 1978; 2:261 271 24. Kay S, Brooks JW: Benign mixed tumor of the trachea with seven-year follow-up. Cancer 1970; 25:1178-1182 25. Greenfield H, Herman PG: Papillomatosis of the trachea and bronchi. A JR 1963; 89:45-50 26. Rosenbaum HD, Alavi SM, Bryant LR: Pulmonary parenchymal spread of juvenile laryngeal papillomatosis. Radiology 1968; 90:654-660 27. Glazer G, Webb WR: Laryngeal papillomatosis with pulmonary spread in a 69-year-old man. A JR 1979; 132:820822 28. Randolph J, Grunt JA, Vawter GF: The medical and surgical aspects of intratracheal goiter. N Engl J Med 1963; 268:457-461 29. Dowling EA, Johnson IM, Collier FCD, et al: Intratracheal goiter; A clinico-pathologic review. Ann Surg 1962; 156:258-267 30. Fraser RG, Pare JAP: Diagnosis of Diseases of the Chest, vol. 11 (ed 2). Philadelphia, Saunders, 1978, pp 1013-1026 31. Hajdu SI, Huvos AG, Goodner JT, et al: Carcinoma of the trachea: clinicopathologic study of 41 cases. Cancer 1970; 25:1448-1456 32. Janower ML, Grillo HC, MacMillan AS Jr, et al: The radiological appearance of carcinoma of the trachea. Radiology 1970; 96:39-43 33. Pradhan D J, Rabuzzi D, Meyer JA: Primary solitary lymphoma of the trachea. J Thorac Cardiovasc Surg 1975; 70:938-940 34. Dines DE, Lillie JC, Henderson LL, et al: Solitary
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plasmacytoma of the trachea. Am Rev Resp Dis 1965; 92:949-951 35. Rosenberg LM, Polanco GB, Blank S: Multiple tracheo-bronchial melanomas with ten-year survival. JAMA 1965; 192:717 719 36. Yeh T J, Batayias G, Peters H, et al: Metastatic carcinoma to the trachea: report of a case of palliation by resection and Marlex graft. J Thorac Cardiovasc Surg 1965; 49:886-892 37. Zerner J: Metastatic carcinoma (endometrial adeno-
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acanthoma) to the trachea. Report of a successful resection and primary anastomosis. J Thorac Cardiovasc Surg 1975; 70:139 142 38. MacMahon H, O'Connell DJ, Cimochowski GE: Pedunculated endotracheal metastasis. AJR 1978; 131:713714 39. Karasick D, Karasick S, Lally JF: Mucoid pseudotumors of the tracheobronchial tree in two cases. A JR 1979; 132:459 460
O M E general remarks that also apply to tracheal tumors have already been made in the in this Seminar. The following comments apply more specifically to neoplasms. The radiographic differential diagnosis between benign and malignant tumors of the trachea may be difficult, j A mass under 2 cm in length is generally benign; most malignant tumors are more than 4 cm in length. Malignant tumors usually have an irregular surface, extend along the tracheal wall, and invade the adjacent mediastinal structures. Benign tumors are often smooth, rounded, and more localized. It should be noted that any tumor of the trachea, benign or malignant, may extend into and even block a main stem bronchus. Since the term polyp is merely a gross morphologic label, it is not considered a separate entity unless its histologic nature is stated. However, a truly pedunculated lesion is almost always benign (Fig. 1). The presence of calcium does not distinguish a benign from a malignant tumor. Chondroma, hamartoma, bronchial adenoma, and hemangioma can calcify, but so can chondrosarcoma. Although you may not agree, I have arbitrarily chosen to include the bronchial adenomas among the benign lesions, chiefly because of their slow growth, good prognosis, and close radiographic resemblance to other tumors that are always benign.
S Letter From the Editor
BENIGN TUMORS Adenomas
The most frequent adenoma of the trachea is the cylindroma, also called adenoid cystic tumor. It has a predilection for the middle third. It accounts for about 40% of tracheal tumors. 2 It is apparently a different tumor from the skin lesion of the same name. It has a predilection for the middle third of the trachea, and grows slowly. It metastasizes late, chiefly to bone and lung. 3'4 Less frequent is the mucoepidermoid adenoma, composed of mucus-secreting and epidermoid cells. 5'6 Although common in the larger bronchi, carcinoid is infrequent in the trachea. It
Seminars in Roentgenology, Vol. XVlll, No. 1 (January), 1983
is rarely associated with the carcinoid syndrome. 7,8 The adenomas tend to invade the tracheal wall and extend into the adjacent mediastinal structures. The nearby lymph nodes may be involved. Distant metastasis occurs late; even then the course is often prolonged, so that a patient with persistent tumor may live for 10 yr or more in a relatively good state of health. Radiographically the adenomas are a l m o s t always rounded, sessile, smooth-surfaced, and sharply demarcated. It is surprising how much of the tracheal lumen can be encroached on before symptoms of obstruction appear (Fig. 2). Blockage of a main stem bronchus may occur from an adenoma arising in the bronchus (Fig. 3) or lower trachea. Mediastinal extension and lymph node metastases may be detected by a variety of methods, the least invasive of which are esophagography, tomography, and CT. Spindle Cell Tumors
Spindle cell tumors of the trachea or main stem bronchus are not so rare, usually presenting as a sharply defined rounded tumor identical to the adenomas. Mediastinal extension is seldom a feature. Neurinomas of various types, including neurofibroma (Fig. 4) and neurilemoma, may occur in the trachea or main bronchus] The lesion may represent a local manifestation of neurofibromatosis or an isolated tumor, it may occur anywhere along the trachea or in either main stem bronchus. lntraluminal tracheal paraganglioma may secrete hormones that can be detected chemically or functionally. 9 ~ Leiomyoma of the trachea, as elsewhere in the body, is a slow growing lesion that arises intramurally, most commonly in the lower third. From the Department of Radiology, University of Cincinnati College of Medicine, Cincinnati, Ohio. Benjamin Felson: Professor of Radiology, University of Cincinnati College of Medicine. Address reprint requests to Benjamin Felson, M.D., Department of Radiology, University Hospital, Cincinnati, Ohio 45267. 9 1983 by Grune & Stratton, Inc. 0270-9 295/83/1801~0006502.00/0
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BENJAMIN FELSON
Fig. 1. Pedunculated epithelial polyp. The tumor, attached to the wall of the right main stem bronchus, has extended into the trachea on this bronchographic spot film (arrowheads). Later in the study it flipped into the right lower lobe bronchus.
Fig. 2. Cylindroma of the trachea w i t h a right upper lobe metastasis. (A) Plain film. The trachea is slightly less lucent just below the level of the clavicles than it is above and below this level. (B) The tomogram shows a smooth, round, sharply marginated mass which seems to fill the entire tracheal lumen. The patient had recent onset of bouts of "asthma.'"
B
Fig. 3. A fascinating case of carcinoid of t h e left main stem bronchus. The patient had had i n t e r m i t t e n t hemoptysis for several years. (A) PA teleo. The entire left lung is collapsed. The right lung has herniated all the w a y to the left lateral chest wall. The left main stem bronchus shows a cut-off. |B) Left lateral teleo. The heart is displaced far posteriorly by t h e herniated right lung. Congenital absence of the left lung was also given consideration. (C) Tomogram. Branches of right pulmonary vessels (arrowheads) extend across the midline into the aerated pulmonary tissue in t h e left lateral thorax. (D) Arteriogram. The injection was made via a catheter in the lower descending thoracic aorta. "Bronchial arteries" emanating from the aorta (lower arrow) anastomose w i t h left pulmonary artery branches. Retrograde f l o w into the left main pulmonary artery (upper arrow) indicates that there is a left lung.
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Fig. 4. Neurofibroma of the trachea. This oblique tomogram shows a sharply outlined Iobular tumor arising from the posterior trachea wall (arrow). The patient had neurofibromastosis.
BENJAMIN FELSON
Pathologically it has a smooth surface and a broad sessile base. It may have an iceberg configuration, a small component projecting into the tracheal lumen with the bulk of the lesion extending into the adjacent mediastinum. '2'~3 Granular cell myoblastoma is a rare benign tumor of the larynx, trachea, or major bronchi, most common in black females 30-50 yr of age. This lesion closely resembles the other spindle cell tumors grossly. It may be sessile or pedunculated. It is characterized histologically by large granular foamy cells in syncytial masses. The tumor usually arises in the cervical trachea and tends to infiltrate adjacent structures, including the esophagus. It may be multiple, and occasionally undergoes malignant degeneration. ~4-~6 Fibroma usually occurs in the cervical segment of the trachea. It is more common in children. It ususally presents as a solitary welldefined sessile tracheal nodule, but may be pedunculated, j7 Fibrous histiocytoma is the name recently applied to a benign or malignant fibrous tumor,
Fig. 5. Leiomyosarcoma of the lower trachea. (A) AP and (B) lateral tomograrns show a well-defined slightly Iobulated lesion (arrows). Benign spindle cell tumors have an identical appearance. (Courtesy of Col, Sherry Brahman, Walter Reed Army Hospital.)
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most commonly arising in bone but occasionally primary in the thorax or elsewhere. Selection of this name is unfortunate, since it has preempted a term formerly applied to a different tumor of the respiratory tract, also known as xanthoma or pseudotumor, a benign lesion composed of histiocytes and xanthomatous and fibrous tissue. Both types of histiocytoma have been reported in the trachea. !8 Lipoma rarely occurs in the trachea or main stem bronchus. It may be mucosal or mural, round or lobulated, pedunculated or sessile. Because of its small size and location, its fat content cannot be recognized by any of the current radiographic modalities. 7 Malignant spindle cell tumors may closely resemble their benign counterpart, both histologically and radiographically (Fig. 5). Differentiation seldom can be made unless metastases are demonstrated. When the microscopic appearance is clearly malignant, the tumor is grossly and radiographically irregular and resembles tracheal carcinoma. 7J9
Angiomatous Tumors Hemangioma of the trachea is usually an isolated lesion but may be associated with hemangiomas elsewhere in the body. It is the
Fig. 6. Laryngotracheal hemangioma in a child. The Iobulated tumor involves the vocal cords and ventricle and extends into the subglottic region (arrowheads).
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commonest tracheal neoplasm in the pediatric age group, and is rare in adults. Most occur in the upper trachea or extend downward from the larynx. In fact, a solitary laryngotracheal lesion in a child is usually a hemangioma. The hemangioma is generally of the cavernous type. Radiographically it appears as a nodular mass (Fig. 6), occasionally containing phleboliths. As with hemangiomas elsewhere, spontaneous regression may o c c u r . 2~ Hemangioendothelioma is exceedingly rare and has no particular identifying radiographic features. 22 These angiomatous lesions generally show a high degree of vascularity on angiography, sometimes enabling the diagnosis to be suggested. Cartilaginous Tumors 23 Surprisingly only a few solitary cartilanginous tumors of the trachea have been reported. Chondroma is a well-circumscribed, hard smooth-surfaced tumor attached to a cartilaginous ring and covered by normal epithelium. It may involve any level of the trachea. Radiographically it is seen as an intratracheal nodule measuring from a few mm to 3 cm in diameter. The tracheal wall doesn't usually appear thickened, and extratracheai extension is uncommon. In most cases, typical cartilaginous calcification is seen within the tumor. A chondroma of the distal trachea may extend into a main stem bronchus, causing collapse or air trapping. Much that has been said about chondroma applies also to chondrosarcoma, a slow growing tumor that spreads into the mediastinum and metastasizes widely late in its course. As with spindle cell tumors, histologic criteria for malignancy may be lacking. Hamartoma is usually a chondromatous tumor, but contains other components in addition to the cartilage, such as fat, lymphoid tissue, or epithelial elements. Benign mixed tumor of the trachea is also said to contain cartilage and other elements that resemble salivary tissue. 24 Why it is considered different from hamartoma escapes me. In fact, I'm not even sure that the hamartoma is different from the chondroma. Certainly they both contain cartilage and grow at about the same rate. Obviously we are at the mercy of the pathologist in distinguishing among chondroma,
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BENJAMIN FELSON
hamartoma, and mixed tumor, in the trachea as in the lung.
Papillomatosis Papillomatosis is a common disease of children, but has also been occasionally reported in adults.25 27 The condition, of uncertain cause, presents with many small warts in the larynx and sometimes in the upper trachea. Verruca on the hands have been reported in some children. The papillomas have been attributed to viral infection, although no virus has ever been isolated. The disease is a source of misery for the afflicted child, requiring repeated local removal of the recurrent nodules, a difficult and painful procedure. Some of the potent new drugs, such as interferon, are said to be effective in controlling the disease, but past experience suggests that a skeptical attitude be maintained. Impairment of speech by the laryngeal nodules is a common problem. The papillomas have a strong tendency to recur after removal and may occasionally seed distally into the tracheobronchial tree, where they appear histologically identical to the laryngeal lesions. The lower respiratory lesions are always preceded by laryngeal papillomas. The bronchial nodules often excavate; the cavities are said to be lined with ciliated or nonciliated columnar epithelium, z6 Recurrences tend to become less frequent as the child grows, 27 seldom occurring after age 16, but remission may not occur at all. 26 Death may occur from recurrent infection or upper airway obstruction. About 10% of the patients die of bronchogenic carcinoma in early adult life, even after total remission of the papillomas. Most of the adult-onset cases have died of the disease. The radiographic findings of tracheobronchial papillomatosis are interesting and often characteristic. Countless lesions may involve the entire length of the trachea (Fig. 7). The nodules in the lower respiratory tract commonly obstruct some of the bronchi, resulting in one or more areas of lobar or segmental collapse or air trapping, or pneumonia (Fig. 8). These may clear spontaneously or after treatment. Individual nodules may grow to several cm in diameter, becoming visible in the lungs on the plain chest film. These slowly increase in number and size with the passage of time. Most of the
Fig. 7. Papillomatosis of the trachea. AP tomogram shows innumerable nodules 3 - 1 0 mm in diameter involving the entire trachea,
lung lesions eventually excavate, resulting in cystic lesions of various sizes, each having a thin or thick smooth wall. 26 The pattern of multiple large smooth thin-walled cavitary lesions in a young patient is essentially diagnostic of papillomatosis (Fig. 9). The cyst walls are thicker than those of bullae but usually thinner and smoother than the cavities of metastatic neoplasm or granuloma (Fig. 10). Unlike cystic bronchiectasis, these lesions seldom contain fluid and do not enlarge on inspiration or fill with contrast medium on bronchography. Histiocytosis X may also show large cysts, but many contain fluid or detritus. I know of no mechanism that explains the development of these large cysts within pulmonary papillomas. A solitary squamous cell papilloma, different from the above variety, has been described in adults. The tumor arises in the mucosa and protrudes into the tracheal lumen (Fig. 1 1). It is composed of squamous epithelium with a core of
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29
Fig. 8. PapiUomatosis of the tracheobronchial tree w i t h collapse of the right middle lobe and posterior basal segment of the left lower lobe. Note the tracheostomy tube. The lower trachea appears narrowed on the lateral view. Later on, lateral segmental collapse of the left lower lobe appeared.
connective tissue. It may undergo malignant transformation.
Thyroid Tumors Ectopic thyroid tissue, normal histologically, may be found in the tracheal wall, protruding into the lumen. It may undergo goitrous change,
or even become malignant (about 10%). Intratracheal thyroid tumor is not common but does account for 7% of all tracheal tumors. Women are affected three times as often as men. It is more frequent in the endemic goiter areas of Europe, namely Germany and Switzerland. Multiple nodules are rare, but in over two-thirds of
30
BENJAMIN FELSON
Fig. 9. Papillomatosis of the lower respiratory tract. (A) Lateral view in 1965 shows multiple nodules, some of which are cavitating (arrows). (B) Lateral view in 1972. The lesions ( a r r o w s and a r r o w h e a d s ) are larger and more numerous. All a r e cavitated. (C) PA teleo, 1972. These multiple thin-walled e m p t y cysts a r e diagnostic of papillomatosis in a youngster.
the cases concurrent goitrous enlargement of the normally placed thyroid gland is noted. There is often a connecting bridge between the two masses through the tracheal wall. The combination of cervical goiter and airway obstruction should suggest intratracheal thyroid tumor. The intratracheal mass is often broad-based and smoothly rounded, usually protruding inward from the left posterolateral subglottic wall. 28'29 Intrathoracic goiter alone may displace or compress the trachea to a remarkable degree,
usually without causing symptoms. Invasion of the trachea by carcinoma in the normally sited thyroid gland is sometimes encountered. MALIGNANT TUMORS Carcinoma
Tracheal carcinoma is an infrequent lesion, accounting for less than 1% of carcinomas of the respiratory tract. 3~Average age of the patients is about 55 yr, and there is male preponderance. In
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Fig. 10. Papillomatosis of the lung in an adult. M a n y small cysts, some w i t h fairly thick walls, are present.
31
il
25% of the patients, the tracheal carcinoma is accompanied, preceded, or followed by a second primary carcinoma in the upper respiratory tract, lung, or digestive tract. Hemoptysis is commonly the first symptom of tracheal carcinoma, but the patient may present with dyspnea, wheezing, or dysphagia. Most of the patients have stridor. Grossly, the tumor may be exophytic, infiltrative, or ulcerated. It may arise from any level in the trachea, and involve only a short segment or
Fig. 11. Solitary squamous papilloma. Lateral tomogram, The large nodule (arrow) almost completely blocks t h e trachea. (Courtesy of Dr. R. T. Rainke of Houston.)
Fig. 12. Small round cell carcinoma of the lower trachea w i t h extension into both main stem bronchi. The carinal and right hilar nodes are involved. (Courtesy of Dr. Robert H. Choplin, Bowman Gray School of Medicine, Winston-Salem, NC.)
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extend along the wall for a considerable distance. The tumor may circumnavigate the trachea like a napkin ring or be confined to one part of the wall. It may involve one or both main stem bronchi (Fig. 12). All histologic varieties are encountered; squamous cell carcinoma is the most common, adenocarcinoma and oat cell carcinoma less frequent. Any grade of microscopic differentiation may occur. Adenocarcinoma is said to grow larger and to penetrate more deeply into the surrounding tissue than the other histologic types. 7'3~ Invasion of the mediastinal soft tissues, spread to lymph nodes, and extension into the esophagus are common. A sinus tract or fistula may develop. Seeding into the lung via the bronchial tree occasionally occurs. Most often the spread is via the blood stream to lung, bone, liver, or brain. Radiographically the tumor is usually irregular (Fig. 13), lobulated (Fig. 14), or annular; most are located above the aortic arch. 32 As stated, the longitudinal and horizontal dimensions of tracheal carcinoma vary considerably. Spread into the mediastinum is often indicated by displacement of adjacent air-bearing pulmonary tissue. The barium esophagram (Fig. 15) and CT (see p. 56) usually give a more vivid demonstration of this spread and help to stage the lesion# ~
Fig. 13. Carcinoma of the trachea. The tracheogram shows an irregular exophytic tumor almost completely blocking the trachea (arrowhead).
BENJAMIN FELSON
Fig. 14. Carcinoma of the trachea. This penetrated grid film shows an elongated tumor extending along the left wall of the trachea,
Other Primary Malignant Tumors Lymphoma of the trachea, primary or as part of a disseminated process, is rare and has no distinguishing gross pathologic or radiographic features except for disproportionate lymph node enlargement. Extension into the trachea from adjacent lymphomatous nodes may occur. 33 As already noted, malignant spindle cell sarcoma usually shows the same radiographic signs as the benign form (Fig. 5), although mediastinal invasion may be more extensive. As stated earlier, chondrosarcoma also resembles its benign counterpart radiographically. It commonly shows considerable flocculent calcification. Any of the sarcomas may show widespread metastasis. Solitary plasmacytoma is a well-documented but rare lesion of the upper respiratory tract. It may arise in the trachea, where it usually presents pathologically and radiographically as a rounded or lobulated mass. It may invade surrounding structures and metastasize to lymph nodes. It occurs late in life and commonly eventuates in multiple myeloma of the skeleton. 34 Other malignant tracheal tumors are ex-
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33
Fig. 16. Schneiderian polyp of lower third of the trachea. The enlarged carinal nodes w e r e involved by sarcoidl
tremely rare. In carcinosarcoma, the connective tissue elements of a carcinoma are clearly sarcomatous. It appears as a sessile polypoid mass that invades the surrounding tissues. Schneiderian tumor is a malignant lesion that usually arises from the mucous membrane of the nose, but occasionally occurs in the trachea, where it forms a sessile or pedunculated polypoid tumor (Fig. 16). Most primary malignant tumors of the trachea are unresectable because of their spread along the trachea or into the mediastinum, where they often invade the esophagus, lung, or great vessels. CT is especially helpful in demonstrating the extension of these tumors and staging them.
Metastatic Neoplasm Fig. 15. Carcinoma of the trachea invading the esophagus. (A) PA teleo film shows the primary tumor (*), with carinal nodes located more distally. Note the abrupt opacification in the subclavicular segment of the trachea. (B) Barium swallow. The upper part of the esophageal defect was the site of invasion. Most of the defect represented extrinsic pressure from the primary tumor and the carinal nodes.
Metastasis to the trachea, while not a common event, is an interesting one. How and why does a distant maligant tumor implant in the tracheobronchial mucosa? Nobody seems to know for sure, but here is a logical explanation: a tumor microembolus may bypass, traverse, or originate
34
BENJAMIN FELSON
Fig. 17. Metastatic neuroblastoma of the trachea. This child had intractable " a s t h m a , " and conventional films (A) and (B) w e r e interpreted as normal on several occasions, although the tracheal lesion is visible (arrowheads), (C) Overexposed AP film shows the tumor more clearly (arrow),
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35
Fig. 18. Carcinoma of the lung w i t h extension into t h e trachea (arrow). Collapse of the entire left lung. The t u m o r appeared to arise in the left main bronchus and protrude upward into the trachea.
Fig. 19. Carcinoma of t h e esophagus w i t h extension into the trachea (arrowheads), proved at autopsy.
in the lung and deposit in an endartery within the mucosa. Metastasis may be solitary or multiple, sessile or pedunculated. As with bronchial metastasis, the primary site is most often hypernephroma, with melanoma, breast carcinoma, and colon next in line. However, any malignant tumor may on occasion metastasize to the tracheobronchial mucosa (Fig. 17). 35 38
Thyroid carcinoma commonly involves the tracheal wall and may invade its lumen. Severe respiratory obstruction may ensue. Implantation or extension into the upper trachea from laryngeal carcinoma is fairly frequent, especially following tracheostomy or laryngectomy. Bronchogenic carcinoma (Fig. 18) and esophageal carcinoma (Fig. 19) also commonly invade the trachea. A tracheoesophageal fistula
Fig. 20. Inspissated mucus attached to the tracheal wall (arrow). The lesion remained for several months before being coughed up.
Invasion From Extrinsic Tumor
36
BENJAMIN FELSON
m a y d e v e l o p s p o n t a n e o u s l y or a f t e r r a d i a t i o n . A t t i m e s it is difficult to d e c i d e if a t r a c h e a l t u m o r is p r i m a r y o r i f it is s e c o n d a r y to a c o n t i g u o u s n e o p l a s m ( c o m p a r e Figs. 15 a n d 19). DIFFERENTIAL DIAGNOSIS
A variety of conditions may simulate neop l a s m o f t h e t r a c h e a . M a n y o f t h e s e a r e disc u s s e d e l s e w h e r e in t h i s S e m i n a r . H o w e v e r , seve r a l lesions d e s e r v e s p e c i a l c o m m e n t .
A g l o b o f i n s p i s s a t e d m u c u s m a y a d h e r e to t h e t r a c h e a l w a l l a n d r e m a i n a t t a c h e d for a c o n s i d e r a b l e p e r i o d o f t i m e ( F i g . 20). 39 R a d i o g r a p h i c a l l y it a p p e a r s as a s m a l l n o d u l e p r o t r u d i n g f r o m t h e mucosal surface into the tracheal lumen. If not r e m o v e d b e c a u s e of s u s p i c i o n o f n e o p l a s m , it will eventually disappear. The mucus may be the r e s u l t o f i m p a i r m e n t o f cilial a c t i o n or a b n o r m a l ity o f t h e m u c u s itself, as in a s p e r g i l l u s s e n s i t i v i ty. A s i m i l a r f i n d i n g m a y o c c u r w i t h a s m a l l a d h e r e n t f o r e i g n b o d y , s u c h as a seed.
REFERENCES
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