[Melanoma of the anal margin]

Primary anal mucosal melanoma is rare and is associated with a poor prognosis. The observation of a case of anal melanoma at a localized stage in a woman led us to analyze recent data from the literature on therapeutic alternatives.

A 49-year-old woman presented with a pigmented swelling of the anal margin that had begun three months earlier. Complete local excision of the tumour was performed with the conservation of the anal sphincters. Histological examination revealed SSM mucosal melanoma. Abdominoperineal resection was finally performed because of tumoural invasion of the lateral margins. Staging assessment was normal. Half-yearly MRI monitoring of the pelvis was proposed and at nine months no relapse was seen.

The unusual and misleading symptoms often account for the late diagnosis and poor prognosis of anal melanoma. Treatment is not well defined: local excision with conservation of the anal sphincters is recommended as first-line therapy, but the surgical technique is controversial. Abdominoperineal resection is recommended if the surgical margins are invaded, in the case of local recurrence or if the tumour is inaccessible. The place of adjuvant therapies remains to be defined. More recently, the discovery of mutation in c-KIT mucosal melanoma has allowed the use of biotherapy. Our observation underscores the importance of early detection of anal melanoma by all practitioners concerned in view of its aggressiveness and we report the difficulties of therapeutic management in the absence of established guidelines.