Malignant melanoma of the anorectum: report of four cases.

Four cases of anorectal malignant melanoma are reported in this paper. All patients underwent an abdominoperineal resection with lymph node dissection for a curative operation and received postoperative chemotherapy with dacarbazine, ranimustine, and vincristine, either with or without interferon-beta. One of these patients has been observed for more than 6 years postoperatively without any evidence of recurrence. The other three patients had advanced diseases at the time of diagnosis, and died within 3 years after operation. The prognosis of anorectal malignant melanoma is considered to be directly related to tumor size and depth. Therefore, a staging system and treatments based on the tumor size and depth (or thickness) are needed.