Published online Jun 6, 2019. doi: 10.12998/wjcc.v7.i11.1337
Peer-review started: January 25, 2019
First decision: January 30, 2019
Revised: February 19, 2019
Accepted: March 16, 2019
Article in press: March 16, 2019
Published online: June 6, 2019
Anorectal melanoma (AM) is an extremely rare malignant tumor originating from anorectal melanocytes with a poor prognosis. AM has been reported to have a much lower incidence than cutaneous or choroid melanoma, accounting for 0.4%-1.6% of all melanomas.
We report a 76-year-old female patient diagnosed with anorectal malignant melanoma by colonoscopy and biopsy. Intraoperative examination revealed two distinct anorectal tumors, one melanotic and another amelanotic, as well as two pigmented mucosal zones at the dentate line level. Abdominal perineal resection was performed. A pathological report confirmed all four lesions to be melanomas. Postoperatively, we followed an immunotherapy protocol targeting PD-1 (nivolumab). The patient had 24 mo of disease-free follow-up upon completion of nivolumab treatment.
This is the first reported case presenting coexistence of pigmented and unpigmented AMs in the same patient.
Core tip: Anorectal melanoma (AM) is an extremely rare malignant tumor. We report a 76-year-old female patient diagnosed with anorectal malignant melanoma by colonoscopy and biopsy. Intraoperative examination revealed two distinct anorectal tumors, one melanotic and another amelanotic. Two satellite melanotic implantations were also found in the near mucosal area. This is the first reported case presenting coexistence of pigmented and unpigmented AMs in the same patient and may contribute to further prognostic factor studies in the future research.