[Anorectal melanoma].

Anorectal melanoma is a malignant lesion constituted by melanoma-producing cells which has a very poor prognosis. It is a rare proctologic pathology, representing 0.5-1% of anorectal tumors. It is predominant in females and in the sixth and seventh decades of life. The evolution is more benign in elderly patients due to hormonal factors. The diagnosis is histological and the treatment is surgery, with radical resection being suggested for shallow lesions, and local excision if lesions are deep and the disease is disseminated. We present a case of anorectal melanoma in a 76-year-old woman which had an unusual location on the right anterolateral face of the rectal ampulla. The histological study demonstrated the presence of intracytoplasmatic melanin deposits (Fontana-Mason stain). Abdominoperineal resection of the anus and rectum was performed, confirming the absence of lymph node or hepatic involvement.