Vaginal melanoma: a clinicopathologic and immunohistochemical study of 26 cases

Abstract

Malignant melanomas of the vagina are rare tumors. In this study we present the clinicopathologic features and immunohistochemical analysis of 26 such cases seen in our institution over a period of 30 years. The patients' age ranged from 38 to 90 years (mean 60 years); three patients were premenopausal. Ethnicity was known in 24 patients: 20 white, 2 hispanic, 1 black, and 1 Asian. The most common presenting symptom was vaginal bleeding, followed by vaginal mass. Grossly, the tumor was polypoid-nodular in the majority of cases. The neoplastic cells were epithelioid in 15 cases and spindled in three cases; eight cases had both cell types. Vascular-lymphatic invasion was seen in six cases and perineural invasion was seen in four cases. S-100 was strongly and diffusely positive in 25 of 26 cases (96%). HMB-45 was strongly positive in 16 (62%), 3 (11%) were focally positive, 1 case showed a rare positive cell, and 6 (23%) were negative. With MART-1, 20 cases (77%) were strongly positive, 1 (4%) showed a rare weakly positive cell, and 5 (19%) were negative. Twenty-one cases (81%) expressed tyrosinase and 20 (77%) expressed microphthalmia transcription factor. Twenty cases were Chung's level IV, 3 were level III, and 2 were level II. The patients were treated as follows: anterior exenteration with or without lymph node dissection and with or without radiotherapy (RT) or chemotherapy (CT) (7 cases), wide local excision with or without lymph node dissection and RT/CT (10 cases), hysterectomy with vaginectomy with or without RT/CT (3 cases), vaginectomy with RT (1 case), RT (1 case), and RT and CT (1 case). One patient had palliative RT for the brain metastasis only. Follow-up was available in 23 patients ranging from 3 to 276 months (median 18 months). Local recurrence after primary treatment was seen in six patients and distant metastases in 11 patients. Fifteen patients died of the disease (3-83 months), 4 have no evidence of disease (5-24 months), and 4 are alive with disease (6-276 months). This study confirms the poor prognosis of patients with vaginal melanoma. S-100 remains the most sensitive marker for these tumors. HMB-45 is negative in 23% cases of vaginal melanoma. Tyrosinase and MART-1 are useful markers when S-100 is negative or only focally positive.