A case of rapidly progressing anorectal malignant melanoma

We report here a case of rapidly progressing anorectal malignant melanoma. A 66-year-old man was admitted to our hospital due to bowel abnormalities and anal pain. Detailed gastrointestinal examination revealed a nigrities-like type 1 tumor that occupied a semicircle in the intestinal lumen from the lower rectum to the anatomical anal canal. We diagnosed anorectal malignant melanoma from a biopsy of the tumor. For the first time, we performed abdominoperineal resection. DAV-feron chemotherapy was administered from 18 days after the operation. However, multiple liver metastases, multiple lung metastases, and multiple skin metastases appeared in the early phase after the operation. Metastases increased rapidly and the patient died 138 days after the operation.