Metastatic Ovarian Tumor of Vulvar Malignant Melanoma in a 43-Year-Old Woman: A Case Report and Literature Review

An ovarian malignant melanoma sometimes occurs from ovarian teratoma. Ovarian metastatic malignant melanoma is extremely rare. We describe a patient in whom vulvar melanoma (previously resected) metastasized to the ovary, making ovarian metastatic malignant melanoma. A 43-year-old Japanese woman was referred to us because of left ovarian tumor. She had undergone resection for malignant melanoma on the right labia minora with inguinal lymph node metastasis (pT1bN1aM0, stage IIIA, FIGO 2008). Eighteen months after this surgery, CT scans revealed left ovarian tumor and swelled pelvic lymph nodes, with a pelvic examination disclosing a left adnexal solid mass, with normal serum CA125 level (21.7 U/mL). Laparotomy revealed a left solid ovarian tumor measuring 4 cm, which was covered with a smooth grayish capsule. The right ovary, uterus, and pelvic cavity appeared normal. Upon sectioning during the surgery, the cross-sectional surface of the left ovary revealed a dark brown solid tumor. Following an intra-operative frozen-section diagnosis as metastatic melanoma, total hysterectomy with bilateral salpingo-oophorectomy and pelvic lymph dissection was performed. Histological examination confirmed the diagnosis as malignant melanoma metastasis to the left ovary and the obturator lymph node: the same laterality (left) as the primary site. The tumor was entirely composed of malignant melanoma cells with no evidence of teratoma. Combined chemotherapy with dabrafenib mesylate and trametinib was planned based on the positive BRAF mutations. This case highlights the importance that physicians should have high index of suspicion for the occurrence of ovarian melanoma metastasis after melanoma surgery. We also made extensive literature review on this issue, of which description may contribute to better understanding of this condition.