J Thorac Cardiovasc Surg 2008;136:225-227
© 2008 The American Association for Thoracic Surgery
Teratoma with malignant transformation in the anterior mediastinum
Katsuhiko Shimizu, MD, PhDa,*,
Masao Nakata, MD, PhDa,
Yuji Hirami, MD, PhDa,
Takashi Akiyama, MD, PhDb,
Kazuo Tanemoto, MD, PhDa
a Division of Thoracic and Cardiovascular Surgery, Department of Surgery, Kurashiki, Japan
b Division of Pathology, Kawasaki Medical School, Kurashiki, Japan
Received for publication October 26, 2007; revisions received January 4, 2008; accepted for publication January 6, 2008.
* Address for reprints: Katsuhiko Shimizu, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan. (Email: kshimizu{at}med.kawasaki-m.ac.jp).
Malignant transformation of teratoma in the mediastinum is rare. Pathologically, malignant teratoma can be divided into three types: immature teratoma, teratoma with other malignant germ cell tumor components (such as yolk sac tumor, embryonal carcinoma, choriocarcinoma, and seminoma), and teratoma with malignant transformation (TMT).1,2
TMT is a non–germ cell malignant tumor arising from a preexisting mature teratoma. To our knowledge of the literature, TMT in the mediastinum is extremely rare.3,4 This report describes a surgical case of adenocarcinoma arising from a mature, cystic teratoma in the anterior mediastinum.
Clinical Summary
A 43-year-old woman was admitted to the hospital with a mediastinal mass. Eight years previously, she had undergone a medical workup for this mediastinal mass but had refused to heed the recommendation of surgery. At this later admission, she reported a 3-month history of exertional breathlessness. Chest radiography showed a large mass shadow from the mediastinum to the left thoracic cavity; the mass had clearly enlarged relative to its appearance 8 years previously. Contrast-enhanced computed tomography showed a lobulated, cystic mass with a fat component that measured 12 x 9 x 14 cm in the anterior mediastinum to the left thoracic cavity (
Figure 1). The laboratory values were within reference limits. Human chorionic gonadotropin, 
-fetoprotein, and carcinoembryonic antigen levels were within acceptable limits, but carbohydrate antigen 19-9 level was high (707 U/mL).
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Figure 1. Contrast-enhanced computed tomographic scan showing lobulated, low-attenuated mass containing fat component in anterior mediastinum.
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Thoracotomy was performed in July 2007. The tumor, which was located on the anterior mediastinum and the left thoracic cavity and had not invaded the left lung and pericardial sac, was completely excised. The resected tumor was 12 x 9 x 17 cm in size and 820 g in weight. The cut surface revealed a multilocular cyst containing yellowish brown material. The wall of the cyst was 3 to 5 mm in thickness, and a small, pale gray, solid area protruded in part of interior surface of the cyst (
Figure 2, A). Microscopically, although most of the mass was a mature cystic teratoma with necrosis, the solid portion of the wall (18 x 8 mm) was found to be moderately differentiated adenocarcinoma (Figure 2, B). No bone or cartilage tissues were observed, however, and there were no immature teratomatous elements or other germ cell components. The final histologic diagnosis was cystic teratoma with somatic-type malignancy (adenocarcinoma). The patient had an uneventful postoperative course. She has not received adjuvant chemotherapy or radiotherapy and is alive without recurrence 6 months after the surgery.
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Figure 2. A, Macroscopic features of resected tumor. Small, pale gray, solid area (arrow) protrudes in part of interior surface of cyst. B, Microscopic examination of medial part of mass, in which moderately differentiated adenocarcinoma crosses fibrous outer wall (original magnification 10x, hematoxylin-eosin stain).
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Discussion
Teratoma is commonly found both in gonadal organs and at extragonadal sites such as the mediastinal, sacrococcygeal, and pineal regions. TMT is rarely found in any organ, but it is sometimes found in the ovary. According to the literature, malignant transformation occurs in 1% to 2% of ovarian dermoid cysts.5 TMTs are seen more frequently than benign teratomas in older patients, and the malignant transformation involves one of the epithelial elements. The most frequent histologic type is squamous cell carcinoma (75%), followed by adenocarcinoma and carcinoid. On the other hand, little is known about the general incidence and pathologic features of TMT in the mediastinum.
TMT has been classified into two clinical and pathologic types: TMT induced by chemotherapy or irradiation and naturally occurring TMT.3 Almost all cases of TMT are of the former type, and they tend to occur in young patients with an initial presentation of a malignant germ cell tumor. The latter type has rarely been reported. In a review of the literature, naturally occurring TMT was described in only two reports. Morinaga and colleagues3 described a case of TMT with well-differentiated adenocarcinoma, and Jung and associates4 described a case of TMT with poorly differentiated adenocarcinoma. Characteristically, naturally occurring TMT is seen in a mature teratoma of long duration. In our case, the patient had a long history of tumor (>8 years) with no treatment, thus suggesting that malignant transformation may have occurred in a preexisting mature teratoma without any effect of chemotherapy or irradiation. The effect of adjuvant therapy on TMT is uncertain. In this case, we considered adjuvant therapy unnecessary, because the tumor was completely excised and there is no evidence for the benefits of chemotherapy for this rare tumor.
In summary, this report documents a case of TMT (adenocarcinoma) in the anterior mediastinum. Naturally occurring TMT in the mediastinum is extremely rare, and the risk of malignant transformation may be increased with a long-standing, mature teratoma.
References
- Ulbright TM, Loehrer PJ, Roth LM, Einhorn LH, Williams SD, Clark SA. The development of non–germ cell malignancies within germ cell tumors. A clinicopathologic study of 11 cases. Cancer 1984;54:1824-1833.[Medline]
- Ahmed T, Bosl GJ, Hajdu SI. Teratoma with malignant transformation in germ cell tumors in men. Cancer 1985;56:860-863.[Medline]
- Morinaga S, Nomori H, Kobayashi R, Atsumi Y. Well-differentiated adenocarcinoma arising from mature cystic teratoma of the mediastinum (teratoma with malignant transformation): report of a surgical case. Am J Clin Pathol 1994;101:531-534.[Medline]
- Jung JI, Park SH, Park JG, Lee SH, Lee KY, Hahn ST. Teratoma with malignant transformation in the anterior mediastinum: a case report. Korean J Radiol 2000;1:162-164.[Medline]
- Chadha S, Schaberg A. Malignant transformation in benign cystic teratomas: dermoids of the ovary. Eur J Obstet Gynecol Reprod Biol 1988;19:329-338.
