[A Case of Surgically Treated Primary Anorectal Malignant Melanoma Detected by Colorectal Cancer Screening]

Anorectal malignant melanoma(AMM)is a relatively rare disease with an extremely poor prognosis. We experienced a case of this disease detected by colorectal cancer screening and report it here with a literature review. Our 67-year-old female patient was referred to the Department of Gastroenterology at our hospital for a thorough examination of the gastrointestinal tract after an abnormal fecal occult blood count(+/+ on 2 occasions)was noted during a colorectal cancer screening. Lower gastrointestinal endoscopy revealed a small easily bleeding lesion near the anal verge for which endoscopic mucosal resection was performed. A histopathological examination revealed a primary malignant melanoma of the rectum, and the patient underwent abdominoperineal rectal amputation. According to the rules for the treatment of T1b (1,200 μm), N0, P0, H0, M(-), StageⅠ, Cur A colorectal cancer. A histopathological examination of the resected specimen showed no remnant tumor cells. About 2 years have passed since the surgery, and the patient is still alive without recurrence. Considering its characteristics, patients with AMM will require further careful follow-up. Here we summarize our experience diagnosing and treating a case of early-stage AMM.