Abstract: Anorectal malignant melanoma is a rare disease with atypical clinical symptoms and has a high misdiagnosis rate. Combined with rectal touch, endoscopy, ultrasonic inspection, CT, MRI, PET-CT, electron microscopy and the result of immunohistochemistry could help improve the diagnosis rate. This tumor tends to relapse and metastasis with poor prognosis, and there is no effective treatment. We should be on the alert for it, and the main point is early discovery, correct diagnosis, multi-disciplinary comprehensive treatment, in order to improve the survival rate of patients.

Key words: Anal canal, Rectum, Melanoma