1674 Primary Anal Melanoma

Abstract

INTRODUCTION: Primary anal melanoma is a rare and aggressive form of neoplasm account <2 % of all melanomas and <2 % of all anal tumors. Metastatic lesions from primary skin tumor are more common. In either case, diagnosis is challenging because often misdiagnosed as hemorrhoid. Surgical excision is the treatment of choice. We present a case of primary anal melanoma that treated with wide local excision and chemotherapy. CASE DESCRIPTION/METHODS: A 71-year-old Caucasian smoker male with history of hypertension, and bladder cancer in remission presented with anal discharge and tenesmus of two-month duration, not related to bowel movement. Pt denies pain, bleeding, change in bowel habits or diet. Physical exam including anoscopy revealed grade 2 internal hemorrhoid, external hemorrhoid, with 2 × 6 cm pedunculated freely mobile black rectal mass. Last colonoscopy was 8 years prior to the presentation within normal limits. Patient underwent a wide local excision of the mass. Pathology revealed invasive nodular melanoma. Patient underwent colonoscopy with endoscopic ultrasound that revealed no regional lymphadenopathy. patient was started on chemo therapy and adjuvant immunotherapy by oncologist. Patient was seen in follow up visit after eight months with negative metastatic work up. DISCUSSION: Malignant melanomas are the fifth leading cancer in men and the sixth in women in the United States. They are mostly cutaneous with non-cutaneous tumors being rare. Melanoma constitute 1% to 3% of all GI malignancies. It remains controversial as to whether these tumors are true primary tumor or they are metastases from unrevealed or regressed primary cutaneous melanomas. It is important to differentiate primary malignant melanoma from secondary lesions because of the worse prognosis of the first one; they are more aggressive and are usually diagnosed late. due to non specific presenting symptoms, more than 50% of patients have metastatic disease upon presentation. Surgical treatment remains the standard of care with controversy regarding the approach (wide local excision Vs. Abdominoperitoneal excision) depending on the stage of the disease.