Malignant melanoma of the anal canal: a case report

Abstract

Anal melanoma is a rare and aggressive malignancy with early local invasion and high metastatic potential, leading to poor outcomes. Limited to case reports, the literature offers little guidance on standardized treatment. We report a case of a 71-year-old male with a year-long history of perianal pain and painful defecation, following decades of mild anal discomfort. He underwent hemorrhoidectomy for presumed hemorrhoids, but histopathology revealed invasive malignant melanoma. On presentation, per rectal exam showed perianal satellite nodules and black pigmentation of the anal canal. Imaging confirmed anal canal thickening with hepatic and pulmonary metastases. Given the advanced stage and positive margins, the patient was managed palliatively with systemic chemotherapy.