Benign capillary and cavernous hemangioma are common in various parts of the body. They may be well localized and well circum-

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1 Unusual Vascular Tumors of the Mediastinum John M. Baker, M.D." V ascular tumors of the mediastinum are uncommon and are usually not considered in the differential diagnosis. The incidence of malignancy is high, and the so-called benign tumors are often locally invasive and adherent to vital structures. The surgical removal of these tumors is often hazardous and may present serious technical problems. Vascular tumors of the mediastinum may be divided into two major groups, true tumors of vascular origin; and pseudotumors or vascular masses, including aneurysms, diverticuli of the heart, and anomalous vessels. Stout [l 1, 121 has simplified the classification of the true vascular tumors according to their cellular composition. A vascular tumor made up of capillaries alone is called a capillary hemangioma. If the vessels are widely dilated, it is a cavernous hemangioma. A vascular tumor with thicker walls containing smooth muscle cells is termed a venous hemangioma. Occasionally, the capillary hemangioma shows proliferation of the endothelial layer, and this may be called a benign hemangioendothelioma. Similarly, pericytes (specialized contractile cells) scattered along the outer surface of the capillary may heap up as rounded or spindle-shaped cells just outside of the reticulin sheath, giving rise to the benign hemangiopericytoma. The best-known form of the hemangiopericytoma is the glomus tumor [121. The occurrence of angiosarcomas is rare in comparison with the development of benign tumors. Angiosarcomas reproduce features that characterize benign tumors. This report is comprised of three unusual vascular tumors of the mediastinum: a cavernous hemangioma, a capillary hemangioendotheliosarcoma, and a pericytoma. HEMANGIOMA OF THE MEDIASTINUM Benign capillary and cavernous hemangioma are common in various parts of the body. They may be well localized and well circum- From the Sutter Community Hospitals and Mercy Hospital, Sacramento, Calif. *Address: 5301 F Street, Sacramento, Calif. Accepted for publication Dec. 14, THE ANNALS OF THORACIC SURGERY

2 CASE REPORTS: Mediastinal Vascular Tumors scribed, or they may grow slowly and invade contiguous structures. The congenital capillary hemangioma frequently disappears spontaneously. Angiomas of the mediastinurn are rare, with only 70 cases reported in the world literature. They may occur in any part of the mediastinum [3, 6, 10, 131. The incidence of malignancy has varied from 16% to 30% in various series reported [6]. These tumors may be found in all ages from premature infants to the elderly; Ellis [3] believes the incidence of angiosarcoma is higher in the youngest age group. The cavernous hemangioma is encountered most frequently. Hemangioma of the posterior mediastinum may be associated with hemangioma of the vertebral bodies. The latter may cause secondary compression of the spinal cord by direct extension into the spinal canal or by secondary destruction and collapse of the vertebral body [Z, 6, 131. There are no characteristic symptoms or x-ray findings, and angiograms are of no assistance in diagnosis. Rib erosion is often seen with malignant lesions, but erosion may also occur with benign angiomas. Complete surgical excision is the treatment of choice, since all hemangiomas have a high malignancy potential. Such excision is often not possible, however, since many lesions are locally invasive [lo]. CASE 1 W. L., a 38-year-old white female fan dancer, was admitted to Mercy Hospital in October, She complained of dizziness whenever she turned her head to the right, extreme fatigability, shortness of breath on exertion, and dysphagia. Physical examination demonstrated a deviation of the trachea to the right. X-rays of the chest with barium swallow demonstrated a large mass in the left FIG. 1. Preoperative chest x-ray of a 38-year-old woman whose left upper mediastinal mass proved to be a cavernous hemangioma containing a central area of hemangiosarcoma. VOL. 3, NO. 4, APRIL,

3 BAKER superior mediastinum shifting the esophagus and trachea to the right (Fig. 1). The outer edges of the tumor appeared to have a serrated, irregular surface. At surgery, a large, dark red tumor was found filling the superior mediastinum, beginning just above the arch of the aorta and extending into the apex of the chest. The adjacent lung was adherent to the surface of the tumor, and numerous capillaries emerged from the lung to enter the mass. It was covered by mediastinal pleura, and it surrounded the left subclavian artery. A vast number of blood vessels, including large branches from the subclavian artery, fed the tumor on all sides, and branches from the innominate vein and superior vena cava contributed to the venous drainage. The tumor was removed successfully after great difficulty and considerable blood loss. Microscopically, the mass consisted of vascular channels lined by a thin endothelial layer. The vessel walls were formed by a dense, partially hyalinized, collagenous fibrous tissue. In one small area, a sheet of neoplastic cells were found. These cells were large and had large hyperchromatic nuclei. In some areas these cells showed epidermoid characteristics; in other areas, they had papillary structures encircling small vessels. The patient eventually died in April, 1954, of widespread metastases. CASE 2 L. T., a 2%-month-old white male, was admitted to Sutter Hospital in shock on September 17, The child had been perfectly well until the day of entry, when he vomited and became very pale and dyspneic. On physical examination, the patient was in obvious shock. There were signs of a left pleural effusion. X-rays of the chest demonstrated a massive left pleural effusion with shift of the mediastinum to the right. The hemoglobin was 8 gm. Two hundred and thirty cubic centimeters of blood were removed from the left chest, and his condition improved after transfusion. X-rays of the chest taken following the thoracentesis demonstrated a density at the extreme apex of the left chest (Fig. 2). The following morning the patient was again in distress. Another 190 cc. of blood was removed by thoracentesis, and again the child was transfused with 200 cc. of blood. FIG. 2. X-ray showing density at apex of left chest following thoracentesis and removal of 230 cc. of blood from the left pleural space. 360 THE ANNALS OF THORACIC SURGERY

4 CASE REPORTS: Mediastinal Vascular Tumors FIG. 3. Microscopic appearance of the tumor in Case 2, a hemangioendotheliosarcoma. Occasional mitotic figures are present among the clusters of rather solidly grouped cells. A left exploratory thoracotomy was performed, and a broad, flat, dark tumor was found extending out from the mediastinum from the apex of the chest to the fifth rib. The tumor was bleeding from numerous sites. It was friable and densely adherent to the underlying chest wall. An attempt was made to remove the tumor, but excess blood loss occurred; before it could be controlled, the child died. Mkroscopic examination of the tumor demonstrated a highly vascular tumor tissue, the cells of which were atypical. These cells tended to form small vascular spaces, some of which contained blood. In places the cells were grouped in clusters and were separated by vascular connective tissue; however, most of the growth appeared fairly solid. Mitotic figures were present but were fairly rare (Fig. 3). The pathological diagnosis was hemangioendotheliosarcoma. HEMANGIOPERICYTOMA Stout and Murray [ll] published their first description of the hemangiopericytoma in They demonstrated that these tumors arose from an abnormal proliferation of the pericytes, specialized contractile cells in the outer sheath of the capillaries. Unlike the glomus tumor, they do not have a highly organoid structure or the remarkable number of nerve endings. The hemangiopericytoma has a variable histological picture. There is always a profuse proliferation of capillaries, each surrounded by a thick or thin connective tissue sheath, outside of which are the characteristic tumor cells that vary in appearance. Some may be large; others may be small, rounded, or spindle-shaped. Special tissue stains VOL. 3, NO. 4, APRIL,

5 BAKER blacken the capillaries, demonstrate the extravaginal position of the cells, and differentiate these cells from hemangioendotheliomas. These tumors may occur in any part of the body. They have been reported in all age groups. Stout has reported 35 cases, the majority of which were in the subcutaneous and muscular layers, but such tumors have been found in the lung, mediastinum, pericardium, diaphragm, retroperitoneal mesentery and omental tissues, orbit, tongue, and meninges [7, 9, 121. The tumors vary greatly in size and usually are well encapsulated. The rate of growth is variable. Usually, the tumors remain stationary for long periods, but they may grow slowly, and some may metastasize widely [8, 11, 121. The incidence of malignancy of these tumors is high. Six of the 35 reported by Stout [l 1, 121 were malignant, 7 others showed very aggressive growth, and 5 others recurred once or more times because of incomplete excision. McCormack and Gallivan [7] reported pulmonary metastases in 5 of 14 cases, and O Brien [8] in 13 of 23. Most of the malignant tumors were relatively large or located in situations where complete removal was difficult or impossible, and most were in elderly people. A thoracic aortic aneurysm caused by a hemangiopericytoma in the aorta wall was recently reported by Bowles et al. [l]. Surgical excision of the tumor is the indicated treatment if possible, although treatment by irradiation is beneficial in some cases [l, 4, 51. CASE 3 A. M., a 59-year-old Italian logger, was admitted to Sutter Hospital in March, 1957, because of shortness of breath and a mass in the left chest. This man had pneumonia two years previously and had become increasingly short of breath. This symptom had made him unfit for work for the preceding year as well as for any exertion associated with daily living. He was able to sleep lying flat, but had to remain on his left side. During the past year, hypertension had developed. He had lost about 10 pounds. On examination, the patient was a husky, 6-foot, well-developed male weighing 195 pounds. His blood pressure was 190/110. There was percussion dullness noted, and breath sounds were absent over the lower two-thirds of the left lung field. The heart was shifted to the right, and heart tones were extremely distant. No murmurs were heard. X-rays demonstrated a mass filling the lower two-thirds of the left chest with deviation of the heart and mediastinum to the right (Fig. 4). Bronchoscopy and bronchography studies demonstrated this mass to be extrinsic to the lung. A left exploratory thoracotomy was performed, and a huge, firm, dark red tumor was found attached to the anterior midmediastinum by a broad stalk approximately 8 cm. in width and 2 to 3 cm. in thickness. Three very large tortuous vessels 2 to 3 cm. in diameter coursed through the pedicle. The mass filled the lower half of the chest but was not adherent to the diaphragm. The lung was adherent but was easily peeled from the encapsulated tumor. The tumor was removed from the chest after ligation and transection of the pedicle. The postoperative course was uneventful. The patient s symptoms were relieved, and he returned to work with a blood pressure of 150/ THE ANNALS OF THORACIC SURGERY

6 CASE REPORTS: Mediastinal Vascular Tumors FIG. 4. (Left) Posteroanterior x-ray of chest in Case 3 showing mass filling lower two-thirds on left with shift of heart to the right. (Right) Lateral view of the large tumor arising from the anterior mediastinurn. The specimen removed was a bilobed structure weighing 3,520 gm. and measuring 24 x 21 x 11.5 cm. after fixation in formalin. Its color was mottled and varied between red and dark blue-gray. Microscopically, the tumor consisted of cells occurring in cords and ball-like masses. The cells were most commonly spindle forms with scant to moderate granular cytoplasm and oval or fusiform nuclei of moderately coarse granular structure. There were fine to coarse acidophilic fibers between the cells. There was a rich vascular network of capillary size with fairly numerous vessels of large size (5 mm.) grading off to vessels of 1 mm. These vessels consisted of mature endothelial cells resting on a collagenous fibrous tissue. Special stains for reticulin and collagen demonstrated the tumor cells to lie extrinsic to the vascular spaces excluded by the reticulin fibers (Fig. 5). The diagnosis was hemangiopericytoma, probably benign. FIG. 5. Microscopic section of hemangiopericytoma in Case 3 showing the characteristic tumor cells lying extrinsic to the vascular spaces demonstrated by special reticulin stains. VOL. 3, NO. 4, APRIL,

7 BAKER The patient was readmitted to the hospital in February, 1964 (7 years later) complaining of chronic fatigue, pain in the left chest, and a cough occasionally productive of blood-tinged sputum. X-rays of the chest demonstrated a mass 5 X 7 cm. in the left chest adjacent to the diaphragm along the posterior cardiac border. Physical examination was unchanged. His blond pressure was 190/ 100 and weight 195. The patient was reoperated upon, and the left chest was explored. There was a well-encapsulated baseball-sized tumor 7 x 5 x 3.5 cm. adherent to the diaphragm and left lower lobe of the lung. There were numerous vessels supplying the tumor from the adjacent structures. The tumor was extremely vascular but shelled out from its bed and was removed completely. On section, it again had a meaty appearance and microscopically was identical with the original tumor. This was thought to represent a local recurrence of the pericytoma which had not been completely removed during the first surgery. The patient is now symptom free and has no sign of recurrence of the tumor. SUMMARY Three rare vascular tumors of the mediastinum are presented. The incidence of malignancy in mediastinal vascular tumors is high, and local recurrence of benign tumors is common. Surgical excision is the treatment of choice, but it may be difficult and hazardous. REFERENCES 1. Bowles, L. T., Ring, E. M., Hill, W. T., and Cooley, D. A. Hemangiopericytoma in a resected thoracic aortic aneurysm. Ann. Thorac. Surg. 1:746, Callahan, W. J., and Simon, A. L. Posterior mediastinal hemangioma associated with vertebral body hemangioma. J. Thorac. Cardiov. Surg. 51:283, Ellis, F. H., Jr., Kirklin, J. W., and Woolner, L. B. Hemangioma of the mediastinum: Review of literature and report of case. J. Thorac. Surg. 30: 181, Friedman, M., and Egan, J. W. Irradiation of hemangiopericytoma of Stout. Radiology 74:721, Kent, K. H. Hemangiopericytoma: Report of a case with special reference to roentgen therapy. Amer. J. Radiol. 77:347, Leibovici, D., and Oner, V. Hemangioma of the posterior mediastinum. Amer. Rev. Resp. Dis. 86:415, McCormack, L. J., and Gallivan, W. F. Hemangiopericytoma. Cancer 7:595, O Brien, P. O., and Brasfield, R. D. Hemangiopericytoma. Cancer 18:249, Ochsner, S., and Decamp, P. T. Hemangiopericytoma of the lung. Amer. Rev. Tuberc. Pulm. Dis. 77:496, Seybold, W. D., McDonald, J. R., Clagett, 0. T., and Harrington, S. W. Mediastinal tumors of blood vascular origin. J. Thorac. Surg. 18:503, Stout, A. P., and Murray, M. D. Hemangiopericytoma: Avascular featuring Zimmerman s pericytes. Ann. Surg. 26: 116, Stout, A. P. Hemangiopericytoma: A study of twenty-five new cases. Cancer 2: 1027, To&, H., Hagstrom, J. W., and Steinberg, I. Hemangioma of the mediastinum. A,mer. J. Roentgen. 94:580, THE ANNALS OF THORACIC SURGERY