Evidence of ¹⁸F-FDG Utility in Rare Case of Metastatic Anal Melanoma with Prolonged Survival

A 43-year-old woman presented with an anorectal mass at which time excision was performed, and biopsy revealed anorectal mucosal melanoma (AM), anal subtype. Postexcision, 18F-FDG PET/CT identified residual melanoma, confirmed on biopsy. Recurrence was monitored every 3 months using 18F-FDG, which identified a perirectal lymph node 2.5 years later positive for metastatic melanoma. Given the rarity of AM and often delayed diagnosis, patients often present with metastases, resulting in poor prognosis. This unique case of metastatic AM with prolonged survival of 7 years to date supports the implementation of 18F-FDG in the diagnostics and monitoring of AM.