Acral Melanoma in an Irish Population: Clinicopathological Features, Molecular Profile and Implications for Early Detection

Abstract

Acral melanoma (AM) is a rare, biologically distinct melanoma subtype arising on the palms, soles, and nail apparatus that is frequently diagnosed late and carries a worse prognosis than non-acral cutaneous melanoma. Population-specific AM data remain limited outside North America and East Asia, and Ireland’s comparatively homogeneous population has not previously been described. We performed a retrospective, bi-institutional cohort study of 41 AM patients treated at two Dublin tertiary referral centres (2017–2023), using data from prospectively maintained melanoma databases, medical records, and pathology reports. Patients were predominantly older adults (median age 73, range 39–88) with a long delay before presentation: 80.5% reported an enlarging lesion for six months or more before seeking care. Lesions were predominantly located on the foot (73.2%), and acral lentiginous melanoma was the predominant histological subtype (82.9%). Median Breslow Thickness was 3.0 mm, and 75.6% presented with T stage ≥ 3. Amputation was required in 65.9% of patients to achieve adequate margins, 47.4% of those assessed had confirmed nodal disease, and 36.6% developed recurrence. Mutation testing, performed in a subset of tumours, identified BRAF, NRAS, and KIT alterations in a minority of cases, with a substantial proportion classified as triple-wild-type. Despite Ireland’s unique germline background reported in cutaneous melanoma, this Irish cohort’s mutational profile and advanced stage at presentation were broadly consistent with international cohorts. Earlier clinical recognition, standardised nail-unit biopsy technique, and a national melanoma registry could improve outcomes for this rare, high-risk subtype.