Melanoma anal amelanótico. Reporte de caso

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. Post- surgical 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.