Primary anal melanoma with visceral dissemination: a case presentation

Huanay-Martínez D.A.; Bellido-Caparó Á.; Garcia-Encinas C.; Ventura-León A. · Revista de gastroenterologia del Peru : organo oficial de la Sociedad de Gastroenterologia del Peru (2025) · DOI: 10.47892/rgp.2025.454.2027

Resumen

Primary anal melanoma accounts for less than 2% of all melanomas and anal tumors. It is highly aggressive, and its nonspecific clinical presentation can delay diagnosis. Despite advances in immunotherapy, surgical resection remains the only curative treatment in early stages. We report a case of a patient presenting with rectal bleeding and an anal mass, without involvement of the skin, eyes, or gastrointestinal tract. Immunohistochemistry was positive for S-100 and Melan-A. Hepatic and pulmonary metastases were identified, and the clinical course was unfavorable.