[Anorectal malignant melanoma : Treatment recommendations]

Anorectal malignant melanoma is a rare tumor with a poor prognosis. Typical symptoms (bleeding, pain, perianal mass) are characteristic of hemorrhoids. This, together with the high rate of amelanotic tumors, often delays diagnosis. No therapy guidelines exist.

Based on our own experience of surgically treated patients and an extensive literature search, we present a stage-dependent therapeutic concept.

Eight patients (six women) with a mean age of 65 ± 8 years were treated at our institution. Six underwent abdominoperineal resection; two had local excision. Two patients additionally underwent inguinal lymph node dissection. Median survival was 12 months with a disease-free survival of 6 months. Forty treatment studies with a total of 1,970 cases could be identified. Prognostic factors are age, time to correct diagnosis, tumor extent, tumor stage, and perineural invasion. The impact of lymph node metastases and R0 resection varies. Surgery is the only effective therapy. Local excision is sufficient when free resection margins are achieved.

Locally limited tumors should be resected; if possible using local excision. Larger tumors or tumors with sphincter infiltration often require abdominoperineal resection with curative intent. When regional lymph node metastases are present, we advise regional lymphadenectomy of the affected area. In the case of distant metastases, palliative surgery is needed for metastasectomy and in cases of incontinence or refractory pain.