Malignant melanoma metastatic to the ovary. A clinicopathologic analysis of 20 cases.

Twenty cases of malignant melanoma metastatic to the ovary are reported. The patients, whose ages ranged from 21 to 60 (average 37.5) years, typically presented because of abdominal swelling or pain. Approximately 50% of the patients also had metastatic tumor outside the ovary, usually within the pelvis and upper abdomen, at the time of presentation. Twelve patients were known to have had a cutaneous malignant melanoma 1 month to 13 years before their ovarian tumors were discovered, and pigmented lesions had been removed previously from three other patients. Most patients are known to have died within a few years of discovery of their ovarian tumors but two were alive without evidence of disease 5 and 8 years later. The ovarian tumors, which were bilateral in nine cases, ranged up to 20 (average 10.5 cm) in greatest dimension. Six of them were either entirely black or had discernible black or brown foci. The most common microscopic appearance was that of large cells with abundant eosinophilic cytoplasm growing in nodular aggregates or diffusely. Occasional tumors were characterized by small cells with scanty cytoplasm, and in five tumors spindle cells were present. Another pattern was growth in the form of discrete rounded aggregates having a nevoid appearance. Eight tumors contained folliclelike spaces. Major cytologic features of the tumors included prominent nucleoli in 13, cytoplasmic pseudoinclusions in many nuclei in five, and intracytoplasmic melanin pigment in nine cases. In the 10 cases studied immunohistochemically, most of the tumor cells were strongly positive for S-100 protein and fewer cells were positive for HMB-45 in the seven tumors that were stained for this antigen. Melanosomes were identified in the three tumors examined ultrastructurally. These neoplasms often were difficult to differentiate from many other types of tumors, including juvenile granulosa cell tumor and small cell carcinoma, because of the presence of folliclelike spaces.