Epidemiological, Clinicopathological, and Molecular Features of Melanoma in Oman: A single-institution study

Published data on melanoma in Oman are scarce. This study aimed to describe epidemiological, clinicopathological and molecular characteristics of melanoma patients in a single institution in Oman.

This retrospective study included patients with a histopathological diagnosis of invasive melanoma who were assessed at Sultan Qaboos Comprehensive Cancer Care and Research Centre, Muscat, Oman, between July 2021 and February 2025. Data on patient demographics, comorbidities, melanoma type, localisation, stage, key histopathological and molecular characteristics were extracted from electronic clinical charts and quantitatively described.

A total of 31 patients were included. The median age at diagnosis was 52.9 years (interquartile range [IQR]: 41.6-66.0). Patients from the Middle East comprised 90.3% of the cohort (n = 28), while Western individuals accounted for 9.7% (n = 3). Cutaneous melanoma was the most frequent type, observed in 83.9% of cases (n = 26), followed by ocular melanoma in 6.5% (n = 2). Mucosal melanoma, central nervous system melanoma and melanoma of unknown primary site were each found in 3.2% of patients (n = 1 each). Among cutaneous melanomas, acral and skin non-acral subtypes were equally represented, each comprising 41.9% (n = 13). Staging data were available for 27 patients; Stage III was the most common at presentation (40.7%, n = 11), followed by Stage II (29.6%, n = 8) and Stages I and IV (14.8%, n = 4 each). The median tumour mutational burden (TMB) was 4.95 mutations per megabase (IQR: 3.86-6.4). Activating BRAF mutations were detected in 35.0% of tested patients (n = 7/20). Brisk tumour-infiltrating lymphocytes were present in 28.6% of evaluated cases (n = 4/14).

Early-stage diagnosis was uncommon. Acral and sun-unexposed non-acral melanoma subtypes were highly prevalent and median TMB was low. These findings suggest that clinicopathological and molecular features of melanoma in Oman may differ from those in Western and Asia-Pacific countries, with potential implications for treatment and prevention strategies.