Abstract
Mucosal malignant melanoma has a particularly poor prognosis because there are few subjective symptoms in the early stage, and it easily metastasizes because most of these tumors occur in areas where blood vessels are abundant, such as the gastrointestinal mucosa. We report a case of anorectal malignant melanoma diagnosed after local excision and review the literature. An 84-year-old woman was admitted to our hospital because of anal bleeding. She was diagnosed with anorectal polyp on examination, and a transanal resection was performed. Postoperative histological diagnosis confirmed a malignant melanoma, and a vertical positive margin was suspected. An additional resection was performed, but a positive margin on the oral side of the dentate line was suspected this time. We suggested performing an abdominoperineal rectal resection with radical excision, but she did not give permission for this procedure. Because there was no evidence that chemotherapy would improve her long-term survival, she did not agree to chemotherapy as well. Interferon maintenance therapy was performed considering her older age and the lack of distant metastasis. However, local recurrence was observed 6 months after the primary surgery, and multiple liver metastases were observed 8 months after that. The patientʼs progress in this case reconfirmed that the malignancy of mucosal malignant melanoma is high if aggressive chemotherapy is not performed.
