CASE REPORTS

Rupture of a Benign Mediastinal Teratoma Into the Right Pleural Cavity Takane Hiraiwa, MD, Takashi Hayashi, MD, Masanori Kaneda, MD, Takashi Sakai, MD, Shoji Namikawa, MD, Minoru Kusagawa, MD, and Itsuo Kusano, MD Departments of Thoracic Surgery and Pathology, Mie University School of Medicine, Tsu, Japan

A 27-year-old woman with a ruptured mediastinal cystic teratoma had high levels of amylase and carcinoembryonic antigen in cystic fluid. The activity of the amylase is thought to be the most likely cause of the rupture. High levels of carcinoembryonic antigen in pleural fluid are not necessarily indicative of a malignant lesion but may suggest the presence of a ruptured teratoma in patients with mediastinal tumors. (Ann Thorac Surg 1991;51:110-2)

T

he rupture into the pleural cavity of a benign cystic teratoma of the mediastinum is a rare complication. There are few reports of such a rupture [l],and we report here an additional case. A 27-year-old woman was admitted to a neighboring hospital on August 7, 1986, because of the sudden onset of severe right-sided chest pain and shortness of breath. The roentgenogram demonstrated an extensive collection of pleural fluid on the right side. The patient’s symptoms were improved after removal of fluid. However, subsequent chest roentgenograms showed a large, anterior mediastinal tumor (Fig 1)and the patient was transported to our hospital on August 24. On physical examination, abnormal findings were confined to the right chest, which was dull on percussion; breath sounds were decreased but respirations were not labored. The hematocrit was 0.30, but other laboratory findings, including tumor markers, were all unremarkable. Computed tomography of the chest revealed a cystic mediastinal tumor, in which a nonhomogeneous rounded mass was present (Fig 2). Cytologic and microbiological studies of a sample of pleural fluid were negative. The sample contained 116 IU/L of amylase and 160 pgIL of carcinoembryonic antigen (CEA). The preoperative diagnosis was a benign cystic teratoma that had ruptured into the right pleural cavity. A right thoracotomy was performed on November 4. The pleura was generally edematous and moderately thickened. A large cystic tumor, measuring 9 X 7 x 12 cm, lay in the anterior mediastinum and the right lung was dislocated posteriorly. The tumor was firmly attached to

the innominate vein and the thymus. After removal of 200 mL of fluid from the tumor, dissection of the tumor was completed. The point of rupture was not obvious. The patient made an uneventful recovery from the operation. The wall of the cyst was made up of fibrous tissue 2 to 5 mm thick, and there were some short hairs on its surface. The rounded mass in the cyst was 2.4 x 1.7 cm in size and made up of fatty tissue. Microscopic examination revealed that the inner surface of the cyst was lined with stratified squamous epithelium. The cyst wall contained tissues derived from all three germinal layers, as in skin appendages, cartilage, intestinal ducts, and salivary gland. There was no evidence of malignancy. The pathological diagnosis was matured teratoma. Some sections were examined by indirect immunoperoxidase staining for amylase and CEA. Positive staining for amylase was visible in the acinar cells of the salivary gland (Fig 3). Positive staining for CEA was apparent in the ductal epithelium of the salivary gland (Fig 4) and in some portions of the stratified squamous epithelium. Examination of the cystic fluid revealed that it contained 813 IU/L

Accepted for publication June 1, 1990. Address reprint requests to Dr Hiraiwa, Department of Thoracic Surgery, Mie University School of Medicine, 2-174 Edobashi, Tsu-shi, Mie 514, Japan.

0 1991 by The Society of Thoracic Surgeons

Fig I. Chest roentgenogram showing an anterior mediastinal tumor. 0003-4975/91/$3.50

Ann Thorac Surg 1991:51:11&2

Fig 2 . Computed tomography of the chest confirming a cystic mediastinal tumor with a rounded mass in it.

of amylase and 480 p g / L of CEA. The fluid was sterile on culture.

Comment Several explanations have been given for the tendency to rupture of mediastinal teratomas. For example, enlarge-

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ment of the tumor may result in ischemia, necrosis of the tumor, and then rupture. Infection has also been suggested as the cause of rupture. It has also been proposed that the sebaceous materials or digestive enzymes derived from the tumor tissues cause inflammation and necrosis, which result in rupture [2, 31. Sommerlad and associates [4] and Southgate and Slade [5]reported cases of nonruptured cystic mediastinal teratoma in which they detected very high amylase activity in cystic fluid. Sommerlad and associates [4] proposed that digestive enzymes derived from the tumor might cause expansion and rupture of the tumor itself. Southgate and Slade [5] suggested that the tendency of a mediastinal teratoma to adhere to and erode surrounding structures was attributed to proteolytic enzymes produced in the tumor. In our patient, the level of amylase in pleural fluid was not elevated, but it was substantially elevated in cystic fluid. Immunohistochemical study demonstrated that amylase was produced by salivary glandular tissue of the tumor. The disparity between the levels of amylase in both fluids probably occurred because the metabolic clearance of amylase in pleural fluid was very rapid [6]. The tumor was not complicated by infection. In the present case, it is reasonable to suppose that amylase played an important role in rupture. In the present case, although there was no evidence of malignancy, levels of CEA were elevated in samples of pleural fluid and cystic fluid. Immunohistochemical examination demonstrated CEA in the salivary glandular tissues of the tumor. Itoh and co-workers [ 3 ]also-reported that although serum levels of CEA were not elevated, as in our patient, both pleural fluid and cystic fluid contained elevated levels of CEA, and immunohistochemical staining demonstrated CEA in the bronchial epithelium of a mediastinal benign teratoma. Because CEA is cleared more slowly from pleural fluid than from plasma [7], CEA level in pleural fluid was kept high, but not higher than Fig 3 . Positive staining for amylase is seen in the acinar cells of the salizmry gland (arrows). (Imrnunoperoxidase, x200 before 42% reduction.)

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CASE REPORT HIRAIWA ET AL RUPTURED MEDIASTINAL TERATOMA

Ann Thorac Surg 1991:51:11&2

Fig 4 . Positive staining for curcinoembryonic antigen is visible in the ductal epithelium of the salivary gland (arrows). (Immunoperoxidase, ~ 2 0 before 0 42% reduction.)

the level in cystic fluid in the case of teratoma. Shousha and Miller [8] reported a case of testicular malignant teratoma in which they detected CEA as well as a-fetoprotein and human chorionic gonadotropin. They suggested that measurements of levels of CEA might be useful because such levels might reflect the degree of teratomatous differentiation in nonseminomatous germcell tumors. Therefore, elevated levels of CEA in pleural fluid or cystic fluid are not necessarily indicative of malignancy but may suggest the presence of teratomatous elements in cases of mediastinal tumors.

References 1. Cobb CJ, Wynn J, Cobb SR, Duane GB. Cytological findings in a n effusion caused by rupture of a benign cystic teratoma of the mediastinum into a serous cavity. Acta Cytol 1985;29: 1015-20.

2. Tatsumura T, Yamamoto K, Tsuda M, et al. Pleural effusion due to rupture of benign cystic teratoma into left pleural cavity: a review of Japanese literature. J Jpn Assoc Thorac Surg 1983;32:2013-20. 3. ltoh Y, Honda Y, Wakabayashi J, et al. A case of mediastinal teratoma accompanying elevated several tumor markers in the cystic fluid. Jpn J Chest Dis 1988;47951-5. 4. Sommerlad BC, Cleland WP, Yong NK. Physiological activity in mediastinal teratoma. Thorax 1975;30:510-5. 5. Southgate J, Slade PR. Teratomatoid cyst of the mediastinum with pancreatic enzyme secretion. Thorax 1982;37476-7. 6. Salt WB, Schenker S. Amylas+its clinical significance: a review of the literature. Medicine 1976;55:269-89. 7. Nystrom JS, Dyce B, Wada J, et al. Carcinoembryonic antigen titers on effusion fluid: a diagnostic tool? Arch Intern Med 1977;137:875-9. 8. Shousha S, Miller GC. A histochemical and immunohistological study of a testicular malignant teratoma containing embryonic and extraembryonic elements in various stages of development. Histopathology 1984;8:125-34.

Rupture of a benign mediastinal teratoma into the right pleural cavity.

A 27-year-old woman with a ruptured mediastinal cystic teratoma had high levels of amylase and carcinoembryonic antigen in cystic fluid. The activity ...
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