Anal melanoma: Atypical cause of rectal bleeding in an older adult patient

摘要

A 91-year-old man receiving antiplatelet and anticoagulant treatment presented with rectal bleeding and anal pain of 6-month progression. He had no improvement with usual care and topical treatment for a hemorrhoidal crisis. An anal polyp in the posterior raphe was palpated in the dig- ital rectal examination. Colonoscopy identified a 30 mm, purplish, ulcerated sphere-shaped lesion (Fig. 1A and B). Histopathologic study revealed squamous mucosa, with infil- tration of the lamina propria by large fusiform cell nests with melanotic pigment, and immunohistochemistry (positive for HMB-45, negative for K5/6) consistent with malignant melanoma (Fig. 2A and B). No evidence of metastatic dis- ease was found but radical oncologic treatment was ruled out due to advanced age and comorbidity. Palliative surgery was performed, and the patient progressed favorably. After one year, he remains asymptomatic.