Anorectal melanoma associated with colonic metastasis.

A 67-year-old female patient with no medical history presents with pain and increased volume in her right lower limb for the last three weeks. She is admitted with a diagnosis of right-side iliac-femoral-popliteal deep venous thrombosis and bilateral pulmonary thromboembolism. She developed rectorrhagia following anticoagulation. Colonoscopy revealed an exophytic, mamillated, friable, anteriorly ulcerated lesion from the anal margin to the mid rectum (Fig. 1), two lesions with similar characteristics in the ascending colon, and three such lesions at the ileocecal valve (Fig. 2). Histopathology and immunohistochemical studies are consistent with melanoma. Abdominal and pelvic CT and MRI scans show a solidly thickened wall with lumpy contours, heterogeneous structure, and poorly delimited borders in the mid and lower rectum, cecum, and ascending colon. She also has neoplastic-looking adenopathies in the right external iliac chain, right hypogastric chain, and aortic bifurcation. The patient received symptomatic palliative care.