Three Cases of Anorectal Malignant Melanoma Treated with Laparoscopic Abdominoperineal Resection

Abstract

We report three cases of anorectal malignant melanoma (AMM) that were treated with laparoscopic abdominoperineal resection (APR). The first case was a 73-year-old woman with a chief complaint of melena. She was diagnosed with pT1bN2aM0 (9th edition of the Japanese classification of colorectal, appendiceal, and anal carcinoma) and adjuvant chemotherapy was performed after radical surgery. Four months after surgery, lateral lymph node metastasis was found. The second case was a 45-year-old man on hemodialysis with a chief complaint of an anal mass. He was diagnosed with pT2N1bM0 and adjuvant chemotherapy was not performed. Two months after surgery, inguinal lymph node metastasis was found. The third case was a 66-year-old woman with a chief complaint of melena. She was diagnosed with pT1bN0M0 and nivolumab was used as adjuvant chemotherapy for 1 year. She remains alive without recurrence 20 months after surgery. There are reports of 51 AMM cases in which APR was performed in Japan, and these show that regional lymph node metastasis is a risk factor for early distant recurrence after surgery.