Anorectal Amelanotic Melanoma: A Case Report

......................................... Received: 24/07/13 Accepted: 27/08/13 Abstract We present the case of a 60 year old patient suffering pain and the sensation of a foreign body in the anal region associated with traces of blood in stools. Digital rectal exam (DRE) revealed a hardened lesion located on the wall of the anal canal. Colonoscopy revealed a raised proliferating lesion with a blackish color which was about 2 inches in diameter. This was compatible with an anal canal malignancy. We proceeded to a biopsy and immunohistochemistry study which tested positive for S-100 and negative for HMB-45. A multislice helical chest, abdominal and pelvic CAT scan ruled out metastatic tumors and lymphadenopathy. The patient underwent local transanal excision of the partially pigmented tumor. Postsurgical histopathological results confi rmed the diagnosis of malignant anal amelanotic melanoma positive for S-100. The sample tested weakly positive for Melan-A and positive for KI-67. The favorable outcome of the procedure led to the patient’s discharge 3 days after surgery.