A Case of Anorectal Malignant Melanoma with Local Recurrence Six Years after Initial Surgery

Abstract

A 59-year-old female underwent transanal tumorectomy for anorectal malignant melanoma at another hospital. Extended local excision and subsequent chemotherapy were performed at our hospital. Six years and 9 months after the first operation, she visited our hospital because of anal bleeding. Colonoscopy revealed the recurrence of malignant melanoma. She underwent abdominoperineal resection (APR); postoperative anticancer drug treatment was not conducted. Six months after abdominoperineal resection, computed tomography revealed multiple metastases in the lung and liver. As BRAF mutation was not detected in resected specimens, treatment with Nivolumab, a programmed death-1 (PD-1) inhibitor antibody, was performed. After administration of Nivolumab four times, a CT examination was performed and an increase of tumor was observed, so the patient was judged as progressive disease. She did not want further treatment and palliative care was done. She died 8 years and 5 months after the initial transanal tumor resection, 1 year and 5 months after APR. Long-term survival of cases with anorectal malignant melanoma is rare, therefore we report this case of anorectal malignant melanoma, along with a review of the literature.