Primary malignant melanoma of the anorectal region is a rare entity and has a poor prognosis. We report a case of advanced anorectal malignant melanoma with pancreatic metastasis at initial presentation.
A 53-year-old woman presented with bloody stool and anal pain lasting for about 2 months. An elastic soft mass was palpated in the lower rectum, and a biopsy specimen was diagnosed as malignant melanoma histologically and immunohistolgically.
Abdomino-perineal resection of the rectum was performed, but peritoneal dissemination was seen. Histologically the tumor was ranked A2, p1, H0, n2, M1, stage IV. No therapy was added to the patient according to her family's request. After discharge she experienced recurrences in various sites including subcutaneous tissue of the right breast and left inguinal region. A total of six operations under local anesthesia were performed. She had ascites 4 months and she died of carcinomatous peritonitis 6 months after the operation. This case suggests that aggressive operation should be restrained for its advanced cases.