DOI: 10.36347/sjmcr.2015.v03i03.024

Pages: 258-260

Malignant melanoma accounts for 15% of the primary malignant tumors of the anorectal region. However, upto one-third of the anorectal melanomas are amelanotic and cause diagnostic challenges. They are often mistaken for benign anorectal disease. Anorectal melanoma is uncommon and aggressive cancer with unfavourable prognosis. 0.4-1.6 % of all melanomas arise in anorectal region. Most patients are female. The first case of anorectal melanoma was reported by Moore in 1857 and approximately 500 cases have been reported. The main differential diagnosis is from Lymphoma, Undifferentiated carcinoma of the rectum, poorly differentiated squamous carcinoma of the anal canal & small cell carcinoma. A 60 year old female presented with bleeding per rectum, change in the bowel habits and weight loss. Sigmoidoscopy revealed a pedunculated polypoidal mass near the anal verge. Histopathological examination was inconclusive and immunohistochemistry was essential to clinch the diagnosis of amelanotic malignant melanoma.