Melanoma - Vulvar Cancers

Melanoma is the most frequent nonsquamous cell malignancy of the vulva and comprises approximately 5% of primary carcinomas of the vulva. Approximately 400 cases of melanoma of the vulva have been reported, with an overall 5-year survival rate of approximately 33%, irrespective of the therapeutic modality used. Patients with malignant melanoma of the vulva vary widely in age, ranging from 10 to 96 years, with an average age of approximately 60 years. These lesions most often affect the labia minora or the clitoris.

For vulvar melanomas, the FIGO classification usually has been used. This classification is not, however, as good a prognostic indicator as is the depth of invasion. A system for vulvar melanoma analogous to that used by Clark for cutaneous melanoma has been adopted. Levels I to V have been identified, based on the Clark classification. The level of invasion correlates with survival, which varies from 100% for level II to 83% for level IV and 28% for level V.

Two varieties of melanoma have been described: nodular and superficial spreading melanoma. The superficial spreading melanoma is more common and has a better prognosis, with a 5-year survival rate of 71%. Nodular melanoma has a worse prognosis, and this directly relates to its potential for vertical growth. The 5-year survival rate for nodular melanoma, which is more invasive, is only 38%.

The thickness of the tumor also may be useful in evaluating this lesion. Breslow reported a classification using depth of invasion as measured from the skin surface. In his classification, Breslow reported the overall prognosis as excellent and the spread to regional nodes as unlikely for melanomas with a thickness of less than 0.76 mm, measured from the surface to the deepest point of penetration.

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Wide local excision has been recommended for Clark level I and II disease when no palpable regional nodes are present. In a report of 36 melanoma cases, Rose and colleagues noted that wide excision was as effective as radical vulvectomy. Prognosis was better for younger patients, presumably because most had superficial spreading rather than nodular melanomas.

A reasonable approach is to excise a melanoma with a 2 cm margin and without node dissection for cases that are less than 2 mm thick. An excision with a 2 to 3 cm margin combined with node dissection could be performed for more advanced melanomas. An alternative approach for lesions that have extended to Clark levels III, IV, and V is radical vulvectomy with groin and pelvic lymphadenectomy.

It has been reported that melanoma of the vulva can metastasize to pelvic nodes, bypassing the inguinal femoral nodes, but current evidence indicates that pelvic node involvement does not occur without prior inguinal node involvement. A further therapeutic consideration is that patients with melanoma whose pelvic nodes are involved with tumor usually do not survive their disease.