Anorectal melanoma--3 case reports and a review of the literature

Anorectal melanoma is an uncommon disease. Histologically, the tumor may mimic adenocarcinomas, small cell carcinomas, and sarcomas; grossly, the lesion often mimics hemorrhoids. We report 3 cases of anorectal melanoma: a 40-year-old woman with anorectal melanoma with local recurrence after an abdominoperineal resection (APR); a 30-year-old woman with anorectal melanoma and multiple liver metastases returning with multiple masses in the rectum and 2 nodules above and below the left clavicle after receiving chemotherapy; and a 62-year-old woman with inguinal node metastases. The histologic findings in all 3 cases revealed malignant tumor composed of atypical melanocytes diagnosed as malignant melanoma of the rectum. In the first case, APR with pararectal lymphadenectomy was performed. Histopathology revealed nodal metastasis. The patient was noncompliant with chemotherapy and died after several months. In the second case, chemotherapeutic treatment was begun. Seven months after receiving chemotherapy, the patient returned with multiple metastases. The final case was lost to follow-up after referral to an oncologist. Anorectal melanoma is highly aggressive and unresponsive to both radical surgery and local control. Although supplemental therapy may improve quality of life and prolong survival, the 5-year survival rate is 10% with a mean survival time of 15 to 25 months. In the 3 cases presented, metastatic disease was present at the time of diagnosis. At this stage, APR with lymphadenectomy followed by some form of adjuvant therapy is our recommended treatment.