Primary Anorectal Malignant Melanoma: Rare but Highly Lethal Malignancy

Aim: Primary anorectal malignant melanoma (MM) is a rare but highly lethal malignancy. The aim of this study was to present an overview of the clinical features and treatment strategies in patients with anorectal MM.Materials and methods: Nine patients who were diagnosed with anorectal MM between 1998 and 2010 were reviewed retrospectively.Results: The median age of the patients was 51 years (range: 28-75). The sex ratio of male to female was 1:2. The main presenting symptom was rectal bleeding. At the time of diagnosis, 1 patient was stage IV and 8 patients were stage III. All of the patients underwent an abdominoperineal resection. Only 1 patient received adjuvant immunotherapy and 8 patients received palliative immunotherapy or dacarbazine and/or platinum-based chemotherapy. The median progression-free survival was 31 weeks (range: 6-211). Sites of metastasis were the lung, liver, and brain in order of frequency. The median overall survival was 81 weeks (range: 54-229).Conclusion: Clear guidelines for the therapy of anorectal MM have not been established. In the treatment plan of primary anorectal MM, multimodal treatment options involving surgery, radiotherapy, and systemic treatment with chemotherapeutics or biological agents should be considered.