Intrathoracic lipomas

Intrathoracic lipomas Report of three cases and review of the literature with emphasis on endobronchial lipoma Intrathoracic lipomas are rare, benign neoplasms of unknown origin, with symptoms depending primarily on their location and size. They frequently represent an incidental roentgenographic finding and are clinically significant in that they may simulate malignant tumors and, when located endobronchially, may cause irreparable lung damage. Three cases of intrathoracic neoplasms are reported herein, and the English literature on the subject reviewed. In some cases, bronchoscopic examination may yield the diagnosis of endobronchial lipoma but, in general, thoracotomy is required for diagnosis. A more complete classification is suggested and the preferred mode of treatment is discussed.

John Politis, M.D., Akira Funahashi, M.D., Jane A. Gehlsen, M.D., David DeCock, M.D., Bruce F. Stengel, M.D., and Hongyung Choi, M.D., Wood (Milwaukee), Wis.

AthOugh lipomas are the most common benign neoplasmas, occurrence within the thoracic cage is uncommon. The number of intrathoracic lipomas reported in the English literature is remarkably small, primarily in isolated case reports. Despite their rarity, intrathoracic lipomas are frequently clinically significant. They may simulate malignant neoplasms and may cause irreversible lung damage. The symptoms depend on their location and size. With the exception of endobronchiallipomas, in which bronchoscopy may yield the correct diagnosis, intrathoracic lipomas are usually diagnosed by thoracotomy. We report three cases of intrathoracic lipomas encountered in our hospital during the past 2 years, one occurring endobronchially, one located in the mediastinum, and one arising from the parietal pleura.

Case reports CASE I. A 44-year-old man was referred to the Wood Veterans Administration Center because of weight loss and an abnormality on the chest x-ray film. History revealed that in

From the Medical, Surgical, and Laboratory Services, Wood Veterans Administration Center, Wood, Wis., and the Departments of Medicine, Thoracic Surgery, and Pathology, The Medical College of Wisconsin, Milwaukee, Wis. Received for publication Aug. II, 1978. Accepted for publication Oct. 16, 1978. Address for reprints: Akira Funahashi, M.D., Pulmonary Disease Section, Research Service/lSI, Veterans Administration Center, Wood, Wis. 53193.

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the past 20 years the patient had numerous febrile episodes associated with chills and increased sputum production. Several of these episodes were diagnosed as "pneumonia" and managed with various antibiotics, generally with good response. There was a history of chronic cough but no episodes of wheezing, hemoptysis, or chest pain. In the 8 months prior to admission, the patient had an increased amount of purulent sputum and lost approximately 25 pounds. Despite the symptoms, he continued to smoke heavily. Physical examination on admission revealed a slightly tachypneic, middle-aged white man with a temperature of 99° F., blood pressure of 120/85 mm. Hg, respiratory rate of 20 breaths per minute, and a pulse rate of 72 beats per minute. The anteroposterior diameter of the chest was slightly increased. Some dullness was appreciated on percussion over the left lower posterior chest. Breath sounds were decreased over the left mid and lower chest, and coarse rales and rhonchi were heard over the same area. A Grade 2/6 systolic ejection murmur was heard at the left lower sternal border. There was no clubbing or cyanosis, and findings from the rest of the physical examination were essentially normal. The chest roentgenogram on admission revealed an infiltrate in the left lower zone with evidence of partial left lower lobe (LLL) collapse. The left hemidiaphragm was elevated and the trachea and mediastinum were shifted to the left (Fig. I). Careful observation revealed a cutoff of the left main-stem bronchus approximately 2 em. from the main carina. The complete blood count showed leukocytosis (15,700 white blood cells) with a left shift. The rest of the laboratory results were normal. Several sputum smears were negative for acid-fast bacilli and malignant cells. Pulmonary function tests revealed a markedly restrictive ventilatory impairment. The presumptive diagnosis of bronchogenic carcinoma was made and the patient was examined with a fiberoptic broncho-

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scope. At bronchoscopy , a large pinkish gray mass with a smooth surface was found in the left main-stem bronchus approximately 2 em. from the main carina. It caused a 90 percent obstruction of the left main-stem bronchus . The mass was pedunculated and freely movable with biopsy forceps. Brushings and biopsy were nondiagnostic, showing some atypia of the respiratory mucosa but no malign ant process. At thoracotom y, the LLL appeared grossly consolidated. During exploration of the upper lobe, a 1.0 em. subpleural mass was noted in the apical posterior segment. A frozen section of this mass revealed an adenocarcinoma. Because of the malignant lesion of the upper lobe and the essentially functionless LLL. a left pneumonectomy was performed . The patient had an uneventful postoperative cour se . At pathological study, a polypoid mass was observed within the lumen of the left main-stem bronchu s. The mass originated from the bronchial mucosa of the lower lobe bronchus, approximately 0.5 cm . distal to the opening of the superior segment. It was yellowish, soft, and lobulated, had a smooth surface, and was 3.5 by 1.8 by 1.0 em . (Fig. 2). The cut surface of the mass was smooth and tan . Microscopic examination showed that it was lined by respiratory epithelium with focal areas of metaplastic squamous cells. The stroma was composed of fibroadipose tissue, with fat being the main element (Fig . 3). CAS E 2. A 66-year-old white man was referred to the Wood Veterans Administration Center for evaluation of a chest x-ray abnormality. The patient denied any symptoms. He was known to have adult-onset diabetes mellitus and hypertension . Approximately 3 years prior to admission, the patient was involved in an automobile accident and had a blunt injury to the anterior chest wall. Physical examination on admission revealed an obese, elderly white man in no distre ss. Lungs were clear. The heart sounds were distant, but no adventitious sounds were detected. Finding s from the rest of the physical examination were unremark able . The admission chest roentgenogram (Fig. 4) showed a smooth, homogeneous density with a sharp border adjacent to the heart. Lateral projection (Fig . 5) disclosed that the lesion was located anteriorly. Comparison with a previous chest roentgenogram (Fig. 6), taken prior to the automobile accident, revealed that the lesion was already present at that time but had become definitel y enlarged . An electrocardiogram showed nonspecific ST-T changes. A fluoroscopic study of the chest revealed a pulsat ing anterior mediastinal mass contiguous with the left ventricle . Echocardiogram and cardiac scan were nondiagn ostic . Cardiac catheterizat ion showed moderate left ventricular hypokinesis , but no evidence of communication between any cardiac chamber and the lesion. At thoracotomy, a smooth multi lobulated mass was found in the anterior mediastinum adherent to the anterior chest wall. The yellowish and firm mass appeared to arise from the mediastinum by means of a fatty pedicle . The entire mass was excised. It was encapsulated, II by II by 5 em. in diameter, and its surface was smooth and glistening with areas of nodularity. Serial sections showed soft and uniform fatty tissue . Microscopically , multiple sections revealed mature adipose tissue with a capsular surfac e. Scattered fibrous septa with vascular structures were seen with the fatty tissue showing focal calcification .

FV 8'12·77

Fig. I. Admission chest roentgenogram (Case I). A significant volume loss at the left is seen, with elevation of the left hemidiaphragm and tracheal and mediastinal shift to the left. Note the cutoff of the left main-stem bronchus. CASE 3. A 62-year-old white man was referred to the Veterans Administration Center because of gradual onset of paresthesias and weakness of both legs. The admis sion chest roentgenogram (Fig. 7) revealed a well-defined, roughly triangular. extrapleural densit y with its base at the right lateral chest wall at the level of the fifth rib. The patient denied any respiratory symptoms and recalled that several years earlier he had been informed about a "shadow" in the right lung. An ultrasound study revealed a solid mass lesion attached to the right lateral chest wall. Needle aspiration of the lesion was attempted with ultrasound but failed to provide a diagnosi s. At thoracotomy . a soft and ye llowish extrapleural mass arising from the parietal pleura was discovered . The mass was excised with a wide margin of parietal pleura . It was well encapsulated, 5.0 by 4.5 by 3.0 em . Histologically , it was composed of mature , well-differentiated adipose tissue . The patient had an uneventful postoperative course. His neurologic symptom s were due to a spinal cord compression , and a decompressive laminectomy was performed .

Discussion Benign intrathoracic tumors are relatively rare, with lipomas being among the least common . Jensen and Petersen' reported that of the 3,502 pulmonary tumors they reviewed , only 65 (1.9 percent) were benign. There were onl y three instances of lipoma among these benign tumors . In contrast to the frequently multiple

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I

2

•

•

..

1

Fig. 2. Pneumonectomy specimen (Case 1) showing the polypoid endobronchial lipoma arising from the lower lobe bronchus.

Fig. 3. Microscopic picture of the endobronchial mass (Case 1) showing a typical lipoma lined by normal respiratory epithelium. subcutaneous lipomas, intrathoracic lipoma is usually a single lesion. Multiple intrathoracic lipomas have been reported in only two cases." 3 The symptoms produced by these benign tumors depend primarily on their size and location. Endobronchial lipomas due to mechanical obstruction of the bronchus cause symptoms at an earlier stage. A review of the literature indicates that the lipomas seen in the thoracic cage can be grouped as follows: (I) endobronchial, arising from the submucosal fat of the

tracheobronchial tree and growing into the lumen of the bronchus, usually amenable to bronchoscopic examination; (2) parenchymal, usuaIly located peripheraIly, surrounded by lung parenchyma, and with no endobronchial extension; (3) pleural, growing into the pleural space, subpleuraIly or as extrapleural masses ; (4) mediastinal, located in the mediastinum; and

(5) cardiac . Endobronchial lipomas. Although adequate microscopic data are lacking, the first case of endobronchial

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Fig. 4. Admission chest roentgenogram (Case 2). A smooth homogeneou s density adjacent to the heart is seen.

Fig. 6. Chest roentgenogram of same patient (Case 2) taken 6 years prior to his last admission . The left paracardiac mass was already present at that time , but had definitel y increased in size.

Fig. 5. Lateral chest roentgenogram (Case 2) showing the anterior location of the mass.

Fig, 7. Chest roentgenogram (Case 3). A well-defined roughly triangular extrapleural mass is seen at the right.

lipoma is believed to be that described by Rokitansky" in 1854 as an autopsy finding. The first documented case of endobronchial lipoma is that described in 1927 by Kernan, ~ who used a bronchoscope to remove a lipoma of the bifurcation of the trachea in a 50-year-old man. Despite the widespread use of bronchoscopy , endobronchial lipomas remain a rare entity, and their true incidence is uncertain. Among nearly 3,000 consecu-

tive surgically resected lung specimens, only three endobronchial lipomas were found ." Of the 63 cases of benign tumors of the tracheobronchial tree encountered at the Mayo Clinic over a 30 year period , only six (9.5 percent) were endobronchial lipomas ." Only 50 cases of endobronchial lipoma have been reported in the English literature, including the case presented here. The age of the patients ranged from 29

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Table I. Exact location of endobronchial lipomas reported in the English literature No. of cases

Location of endobronchial lipomas

3

Trachea Left main-stem bronchus Right main-stem bronchus Left upper lobe bronchus Left lower lobe bronchus Right upper lobe bronchus Bronchus intermedius Right middle lobe bronchus Right lower lobe bronchus Left side; exact location not specified

IO

3 7 6 9 I 3 2 6 50

Total

Table II. Symptoms in 43 patients with endobronchial lipomas in whom adequate data were available Symptoms Persistent cough Chest pain Dyspnea Hemoptysis Recurrent pneumonias Recurrent febrile episodes, but no documented pneumonias Wheezing Weight loss Asymptomatic

I

No. of cases

I

Percent

35 13 13 12 7 6

81.4 30.2 30.2 27.9 16.3 13.9

5 3 1

11.6 7.0 2.3

Table III. Method of treatment in 47 patients with endobronchial lipomas reported in the English literature Treatment

No. of cases

Removal through bronchoscope Coagulation through bronchoscope Lobectomy Pneumonectomy Bronchotomy

16

Total

2

17 9 3

47

to 78 years, the mean age being 53. There appears to be a definite male preponderance, because 44 of the 50 cases occurred in men (88 percent). All lipomas occurred in the major bronchi; the exact location is shown in Table I. The size (usually 1 to 2 ern. in diameter) is necessarily restricted to the caliber of the bronchiallumen. To our knowledge, the tumor found in our patient (3.5 by 1.8 by 1.0 cm.) is the largest endobronchial lipoma ever recorded. Endobronchial lipomas are usually pedunculated

tumors with a narrow stalk, composed of mature fat cells and covered with normal respiratory mucosa. As in our case, this respiratory mucosa may show squamous metaplasia, apparently the result of chronic inflammation. They usually arise from the fat found in the bronchial submucosa. In only three cases, in which an "iceberg" tumor was found with significant interchondral and peribronchial extension."?" the origin appeared to be fat normally present between the cartilages rather than submucosal fat. As in the case reported here, endobronchial lipomas, although "benign" histologically, may cause bronchial obstruction and irreparable damage to the distal pulmonary parenchyma. In general, the symptoms produced by these tumors depend on the degree of bronchial obstruction they cause. In 81 percent of the cases, cough was the most prominent and usually the earliest symptom. Blood-streaked sputum was reported in 26 percent of the patients. In contrast to the bronchial adenomas, which are highly vascular, lipomas are relatively avascular and tend to produce hemoptysis late in their course, presumably owing to infection distal to the obstruction. II Other symptoms encountered in these patients are illustrated in Table II. The duration of symptoms varied from a few weeks to more than 20 years, the mean duration being 4V2 years. At bronchoscopic examination, the endobronchial lipomas appear as smooth, rounded submucosal tumors, firm, gray, or pale pink, and are usually pedunculated and freely movable. The mucosa is usually intact without any ulcerations. Bronchoscopically, they may resemble adenomas, although the mucosa is much less friable and the color more pale than that of adenomas." All of the reported endobronchial lipomas have been accessible to endoscopic visualization; yet tissue diagnosis by bronchoscopy was made in only 50 percent. Once the correct diagnosis has been established by bronchoscopy, the decision must be made regarding the mode of excision. If permanent changes in the distal parenchyma are unlikely, endoscopic removal of the tumor may be attempted. As seen in Table III, 18 cases (38 percent) were managed by endoscopy. When bronchoscopy fails to disclose the nature of the tumor, endoscopic removal of the tumor is not possible, or if there is sufficient evidence that permanent parenchymal damage has occurred distal to the tumor, thoracotomy should be the next step. If no evidence of irreversible lung damage is found, resection of the tumor via bronchotomy should be attempted whenever possible. On the other hand, if the distal parenchyma appears functionless, resection of the involved area of

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the lung becomes the treatment of choice. Thoracotomy was performed in 29 cases (68 percent). Excision of the tumor by bronchotomy was done in only three patients, 13-1~ whereas, in the remaining 26 patients, resection of lung parenchyma was considered necessary. Seventeen of these patients had a lobectomy and nine had a pneumonectomy. In recent years, there appears to be some tendency toward thoracotomy. Endoscopic excision of the tumor was performed in only one of 14 cases over the past 10 years. Parenchymal lipomas. Lipomas occurring within the lung parenchyma are extremely rare. The first reference to lipoma of the pulmonary parenchyma is that by Buchman, 16 who in 1911 described a right lower lobe lipoma found at autopsy. We found only five cases of parenchymal lipoma in the English literature.?: 9.17-19 It is not surprising that in none of the reported cases was the true lesion recognized until operative removal had been accomplished. Thoracotomy is the only reliable method of diagnosing these tumors. Pleural lipomas. Lipomas originating from the pleura are also very rare. They presumably arise from the submesothelial layers of the visceral or parietal pleura'" and may grow subpleurally, into the pleural space, or extrapleurally. Because of location and slow growth, they frequently remain asymptomatic for years and, in most cases (as in Case 3), are found incidentally on a routine chest roentgenogram. Some patients report symptoms such as an irritating, nonproductive cough, feeling of oppression or heaviness in the chest, back pain, and exertional dyspnea. Pleural lipomas may become rather large before being discovered. In 1962, Koernschild and associates" reported successful resection of a pleural lipoma weighing 4.1 Kg. Preoperative diagnosis is difficult. Percutaneous needle biopsy, especially in cases of extrapleural lipoma, has occasionally been diagnostic. 18. 22 The only reliable method of diagnosis and treatment, however, is exploratory thoracotomy and excision of the tumor. Mediastinal lipomas. The mediastinum appears to be the most common site of intrathoracic lipomas," 21 yet these and other tumors of mesenchymal origin are distinctly uncommon when compared to other mediastinal neoplasms. In reviews of collected series.P: 24 lipomas have been found to constitute only 1.6 to 2.3 percent of primary mediastinal neoplasms. Mediastinal lipomas are predominantly found in the anterior mediastinum. They are true benign neoplasms and should not be confused with the accumulation of fat seen in Cushing's syndrome or during exogenous administration of corticosteroids, a condition known as "mediastinal lipomatosis." Mediastinal lipomas may

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grow to enormous size before symptoms occur. Leopold'" reported on one lipoma weighing l71f2 pounds. As in Case 2 reported here, most mediastinal lipomas are discovered during a routine chest roentgenogram. In the late stages, they may produce symptoms related to their effects upon important contiguous structures. Compression of major bronchi and lung parenchyma may cause dyspnea. Compression of the esophagus giving rise to dysphagia has also been reported." A feeling of substernal oppression has been a common complaint in patients with large mediastinal lipomas. Some patients may have a palpable cervical mass, representing extension of the mediastinal lipoma (cervicornediastinallipoma). As in other intrathoracic lipomas, exploratory thoracotomy is required for an accurate diagnosis. Cardiac lipomas. Cardiac tumors are very rare. Their incidence, based on autopsy findings, has been reported as 0.06 percent for primary tumors" and from 0.25 to 1.0 percent for metastatic tumors.F It has been estimated that cardiac lipomas represent 12 percent of all primary cardiac tumors.t" However, Mahaim'" reported only 14 cases of lipomas in a review of 329 cases of primary cardiac tumors found at autopsy (4.3 percent). Because of overlapping reports, the actual number of reported cardiac lipomas is difficult to ascertain. The first reference in the English literature is that of Brewis.P'' who in 1905 reported a lipoma of the right ventricle found at autopsy in a 7-month-old girl. Several cases of successful surgical removal of cardiac lipomas have been reported.">" In one case.P" a 2,500 Gm. intrapericardial lipoma was successfully removed-the largest cardiac tumor ever reported. Most of the reported cases were extracavitary lipomas, which may remain asymptomatic and clinically unimportant throughout a lifetime and tend to be incidental findings at autopsy. By exerting pressure on the heart, large subpericardial lipomas may cause anginal pain" and may interfere with the normal function of the heart. It is conceivable that lipomas arising in the myocardium may interefere with normal electrical conduction and may give origin to various arrhythmias. Subendocardial lipomas are usually small and sessile. As in other intracavitary tumors, subendocardial lipomas may cause conduction disturbances as well as disturbances of cardiac filling or ejection, imitating symptoms of mitral of tricuspid valvular stenosis. In general, the symptoms and physical signs of cardiac lipomas are nonspecific, as are the electrocardiographic and routine roentgenogram findings. Cardiac catheterization and angiography are extremely bene-

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ficial in the diagnosis, especially of the intracavitary tumors. In recent years, echocardiography has become a very useful noninvasive diagnostic technique. It is especially rewarding to arrive at the correct diagnosis, because cardiac lipomas usually are a resectable lesion and, consequently, a curable form of heart disease. REFERENCES

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4 5 6 7

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9

10

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13 14 15

Jensen MS, Petersen AH: Bronchial lipoma. Three cases and review of the literature. Scand J Thorac Cardiovasc Surg 4:131-134, 1970 Johansson L, Soderlund S: Intrathoracic lipoma. Acta Chir Scand 126:558-565, 1963 Jones EL, Lucey 11, Taylor AB: Intrapulmonary lipoma associated with multiple pulmonary hamartomas. Br J Surg 60:75-78, 1973 Rokitansky C: A Manual of Pathology Anatomy, London, 1854, Sydenham Society, vol I, p 196 Kernan JD: Three unusual endoscopic cases. Laryngoscope 37:62-64, 1927 Horanyi J, Horlay B, Molnar J: Endobronchiales Iipom. Thoraxchirurgie 8:573-578, 1961 Caldarola VT, Harrison EG, Clagett OT, Schmidt HW: Benign tumors and tumor-like conditions of the trachea and bronchi. Trans Am Bronchoesoph Assoc 44:46-69, 1964 Carlisle JC, Leary WV, McDonald JR: Endobronchial lipoma. Report of a case. Mayo Clin Proc 26: 103-106, 1951 Touroff ASW, Seley GP: Lipoma of the bronchus and the lung. A report of two unusual cases. Ann Surg 134:244250, 1951 Crutcher RR, Waltuch TL, Ghosh AK: Bronchial lipoma. Report of a case and literature review. J THoRAc CARD10VASC SURG 55:422-425, 1968 MacArthurCGC, Cheung DLC, Spiro SG: Endobronchial lipoma. A review with four cases. Br J Dis Chest 71:93100, 1977 Bellin HJ, Libshitz HI, Patchefsky AS: Bronchial lipoma. Report of two cases showing chondroitic metaplasia. Arch Pathol 92:20-23, 1971 Som ML, Feuerstein SS: Endoscopic removal of lipoma of the bronchus. Arch Otolaryngol 54:341-346, 1951 Brewin EG: A case of lipoma of the bronchus treated by transpleural bronchotomy. Br J Surg 40:282, 1952 Cockroft DW, Copland GM, Donevan RE, Gourlay RH: Endobronchial lipoma. Two cases and review of the literature. Can Med Assoc J 115:326-328, 1976

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16 Buchman E: Zur Lehre der fotalen lungenatelektase und der fotalen bronchiektase. Frankfurt Z Pathol 8:263-267, 1911 17 Shapiro R, Carter MG: Peripheral lipoma of the lung. Report of a case. Am Rev Respir Dis 69: 1042-1044, 1954 18 Spencer H: Textbook of Pathology of the Lung, New York, 1962, Macmillan Publishing Co., Inc., pp 698-700 19 Plachta A, Hershey H: Lipoma of the lung. Review of the literature and report of a case. Am Rev Respir Dis 86:912-916, 1962 20 Kroecker EJ, Watkins E, Pouget JM: Primary pleural tumors with report of a subpleural hemangiopericytoma. Surg Clin North Am 41:719-726, 1961 21 Koernschild HE, Marchall F, Andrews NC: Intrathoracic lipoma. Report of successful removal of a large tumor. Ohio State Med J 58:1270-1272, 1962 22 Fine EH, Joubert GA: Intrathoracic lipoma. Report of a case. S Afr Med J 27:809-811, 1953 23 Hodge J, Aponte G, McLaughlin E: Primary mediastinal tumors. J THoRAc SURG 37:730-744, 1959 24 Staub EW, Barker WL, Langston HT: Intrathoracic fatty tumors. Chest 47:308-313, 1965 25 Leopold RS: A case of massive lipoma of the mediastinum. Arch Intern Med 26:274-278. 1920 26 Lymburner RM: Tumors of the heart. Histopathological and clinical study. Can Med Assoc J 30:368-378. 1934 27 Friedberg CK: Diseases of the Heart, ed 3. Philadelphia. 1970, W. B. Saunders Company, pp 1707-1720 28 Yater WM: Tumors of the heart and pericardium. Pathology and symptomatology and report of nine cases. Arch Intern Med 48:627-640, 1931 29 Mahaim J: Les tumeurs et polypes du coeur. Etude anatomoclinique, Paris, 1945, Massan and Lausanne, p 586 30 Brewis RA: A case of lipoma in the right ventricle of the heart. Lancet 2:829-830, 1905 31 Maurer ER: Successful removal of tumor of the heart. J THORAC SURG 23:479-485, 1952 32 Crockett JE, Decker D, Reed W, Dunn M, Leger L: Lipoma of the heart. Am J Cardiol 14:394-398, 1964 33 Shumacker HB, Leshnower AC: Extracavitary lipoma of the heart. Operative resection. Ann Thorac Surg 18:411414. 1974 34 Moulton AL, Jaretzki A, Bowman FO, Silverstein EF, Bregman D: Massive lipoma of the heart. NY State J Med 76: 1820-1825, 1976