Acral lentiginous melanoma: a skin cancer with unfavourable prognostic features. A study of the German central malignant melanoma registry (CMMR) in 2050 patients

Abstract

Background: Acral lentiginous melanoma (ALM) is one of the four major subtypes in cutaneous melanoma (CM). Although ALM has a poorer prognosis than other CM subtypes, the prognostic factors associated with ALM have only been verified in small-sized cohorts because of the low incidence of ALM worldwide.

Objectives: To investigate the clinical characteristics of ALM and to evaluate their prognostic values based on a large dataset from the Central Malignant Melanoma Registry (CMMR) of the German Dermatologic Society.

Methods: The Kaplan-Meier method was used to estimate the potential influence of clinical and histological parameters on ALM disease-specific survival (DSS) curves, which were compared using the log-rank test. A Cox proportional hazards model was used to identify independent prognostic factors for DSS.

Results: In total, 2050 patients with ALM were identified from 58 949 patients with CM recorded by the CMMR with follow-up data. In multivariate analyses, age (P = 0·006), ulceration (P = 0·013), tumour thickness (P < 0·001) and tumour spread (P < 0·001) turned out to be significant prognostic factors for DSS in ALM whereas sex, nevus association and level of invasion were not independent factors.

Conclusions: ALM has the same prognostic factors as other subtypes of melanoma. Unfavourable prognosis probably derives from the delay in diagnosis in comparison with other melanoma subtypes.