Amelanotic malignant melanoma arising in an ovarian dermoid cyst KIRSTENBORUP’,KJELDLEISGARDRASMUSSEN’, LARSSCHIERUP’
From the Departments of ’Surgery and 2Pathological Anatomy, Skive Hospital, OK-7800 Skive, Denmark
Acru Obsrrl Ciynecol Scand 1992; 71: 242-244
Malignant transformation occurs in about 2% only of ovarian dermoid cysts. The clinical and histopathological findings in a rare case of primary ovarian malignant melanoma of amclanotic type are presented.
K r y words: arnelanotic malignant melanoma; ovarian dermoid cyst Submitred August 26, 1991 Accrped November 14, 1991
Malignant transformation is an unusual complication of dermoid cysts, occurring in approximately 2 % o f cases (1). Squamous carcinomas and adenocarcinomas are predominant among these lesions (> 85%) (2), but infrequently other types of malignant tumor are encountered, including malignant melanoma. We describe here a case of hona fide primary ovarian malignant melanoma (OMM), which from a diagnostic point of view was particular in requiring immunohistochemical analyses for final identification.
Case report A 66-year-old woman was admitted to hospital with ii %month history of abdominal distention, lower right quadrant pain and slightly elevated body temperature. There had been no vaginal bleeding or discharge. On physical examination she had a small, mobile uterus and a large tumor in the pouch of Douglas. Ultrasonography showed a centrally cystic tumor located behind the uterus (Fig. 1 ) . At surgery a tumor was found, originating from the left ovary. There were signs of tumor spread to the contralatera1 ovary and peritoneal carcinosis. Metastases in the liver and enlargement o f regional lymph nodes were not observed. Hysterectomy and bilateral salpingo-oophorectomy were performed. The postoperActrr Oh.jrrr Gyrwcol Scurlrl 71 (IYY2)
ative course was uneventful. N o additional treatment was offered. Subsequent ultrasonograpic controls showed signs of tumor recurrence and the patient died within 12 months. N o postmortem examination was performed. Neither before nor during the actual disease was there any evidence of malignant melanoma in the skin o r elsewhere. Pathology The uterus was free from malignancy. The tumor from the left ovary measured 18 x 20 cm. It wits grayish. with areas of hemorrhage and necrosis. but with no visible pigmentation. A central cystic cavity contained hair. The tumor cells were large, pleomorphic, with ample non-pigmented cytoplasm. varying nuclear number and size and prominent nucleoli (Fig. 2). Staining for melanin (Fontana) was negative. Apart from hair, no dermoid cyst structures were identified. Immunohistochemically the tumor cells showed positive reactions to antibodies to Vimentin and S-100 protein (both DAKO) as well a s to melanin-specific antibody (Enzo). Negative reactions were obtained with antibodies to cytokeratin (low and high molecular weight), epithelial membrane antigen, leukocyte common antigen and human chorionic gonadotropin (all DAKO). The positive reaction with S-100 protein, however, wiis the
Amelanotic malignant melanoma arising
Fig. I . Photomicrograph showing part of ovarian malignant melanoma with amelanotic, pleomorphic tumor cells. x 100.
most important, because this analysis led to further investigation, and thereby to the diagnosis.
Discussion The great majority of dermoid cysts of the ovary are harmless tumors, and the development of malignant melanoma in this context is generally considered a curiosity. Thus in a comprehensive review from 1957 (1). encompassing 222 examples of malignant transformation in cystic teratomas, only 2 cases of melanosarcoma are mentioned. However, it is worth noting that. since the first case was reported in 1903 (3). there have been an additional 13 case reports and half of these date from the last decade. The clinical significance of ovarian malignant melanomas pertains in part to their aggressive growth, in part to the fact that they may occur in young and middle-aged women (4, 5 , 6, 7 , 8). Some cases have also been associated with pregnancy (4, 9, 10). Suspicion of OMM should arise in the case of a rapidly growing, ultrasonographically cystic ovarian mass and further increase by the finding at laparotomy of a bluish-black tumor associated with a dermoid cyst. However, the case presented, as well as a recently published similar case from Japan (8), demonstrate that OMM can be amelanotic. In this situation the melanoma cannot be distinguished grossly from other malignant neoplasms. Histologically, various other possibilities, such as anaplastic carcinoma or dysgerrninoma, have to be considered and final diagnosis may depend on the results of immunohisto17*
chemical analyses and eventually electron microscopic demonstration of premelanosomes in the tumor cells (8). As for immunohistology, no single antibody is specific for malignant melanoma, and for practical purposes a panel o f immunological markers, including antibodies to cytokeratin, vimetin, S-100 protein and melanin, should be employed. The distinction between primary and secondary (metastatic) malignant melanoma in the ovary may be of some relevance to both prognosis and choice of therapy. Yet a definitive solution to this problem may be difficult to achieve in some cases. O n e reason is that primary cutaneous malignant melanoma may regress spontaneously, leaving only metastatic deposits ( 1 1). Additionally, cutaneous malignant melanoma metastatic to bilateral ovarian dermoid cysts has been reported (12). Finally, in cases of malignant melanoma with multi-organ involvement, the definition of what is primary and secondary becomes arbitrary. Consequently, some authors regard the presence of junctional melanocytic activity in the dcrmoid cyst adjacent to OMM as a major criterion for a primary OMM (12, 13). We find this attitude too restrictive, excluding all such cases (incl. the present one) which have a distinctly local spread and show no evidence of previous or actual malignant melanoma at other sites, but where dermoid cysts structures are almost completely destroyed by the malignant overgrowth. The treatment of OMM is primarily surgical. Postoperative combination chemotherapy has been attempted in a few patients. with some degree of success (8, IS), and in a case of restricted, non-metaActu Oh.rrei G'yniwd Scurirl 71 (1992)
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static disease, m o r e t h a n 2 y e a r s of recurrence-free survival h a s been r e p o r t e d (8). O t h e r w i s e , t h e prognosis IS generally p o o r
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