Primary Anorectal Melanoma at a South Asian Tertiary Care Center: A Single-Institution Brief Report

Cutaneous melanomas are relatively well characterized, and early-stage disease carries a good prognosis; however, advanced melanoma remains challenging despite therapeutic advances. Primary anorectal melanoma (ARM) is a rare entity with a decidedly aggressive course, representing less than 2% of all anorectal malignancies with a comparatively low incidence in the Asian population compared to Western populations. Lack of definitive treatment guidelines with frequent local and systemic metastatic recurrences lends a bleak prognosis. The objective of this study is to describe the clinicopathological features, management, and outcomes of primary anorectal melanoma in a tertiary care cohort in Pakistan. We conducted a retrospective study aimed at reviewing patient records over three years from January 2020 to December 2022 at a tertiary care hospital in Karachi, Pakistan. Of the seven patients, a nearly equal gender predilection was seen. More than half of the cohort had metastatic disease at the time of diagnosis. Only two patients had identifiable molecular alterations — one with a KIT mutation and another with PD-L1 overexpression. Four patients received nivolumab as systemic therapy. The study identified a poor prognosis of this disease, with more than half receiving palliative care or died during follow-up, eventually. Early diagnosis and treatment with prolonged survival remains a challenge with anorectal melanomas. Inherently aggressive, these tumors have a dismal prognosis. Targetable mutations such as KIT may represent potential therapeutic avenues; further prospective studies are required.