Acral Lentiginous Melanoma Presents Distinct Clinical Profile with High Cancer Susceptibility

Background: Acral lentiginous melanoma (ALM) is a distinct histological variant of cutaneous melanoma that presents a genomic profile different from the other variants. Our aim was to explore the distinctive clinical, pathological, and epidemiological characteristics of ALM.

Patients And Methods: A series of 978 patients with primary cutaneous melanoma was selected from a single referral center. Among these, 79 were located on acral sites and 46 presented an ALM. This group was compared with a group composed of 932 patients with the remaining three most frequent cutaneous melanoma variants.

Results: The ALM differed significantly from other variants: in an older age at diagnosis (65.52 vs. 51.79 years), a lower number of common (88.2 vs. 55.8%) and atypical nevi (95.0 vs. 80.2%), a predisposing genetic trait to cancer (22.2 vs. 7.1% had a personal history of other non-cutaneous malignancies and 58.1 vs. 36.4% had at least one first degree relative with non-cutaneous neoplasia) and lower number of sunburns (88.2 vs. 47.4% remembered none). Also, the tumors were thicker (mean of 2.94 vs. 2.03 mm), more frequently ulcerated (74.2 vs. 23.9%) and with perineural invasion (8.0 vs. 1.5%), had lower degree of inflammatory infiltrate (36.8 vs. 7.5% was absent) and were less frequently associated with a previous melanocytic lesion (8.3 vs. 32.6%). Differences were kept even after age-adjusted analyses.

Conclusions: Our results, from a clinical and epidemiological point of view, support recent data on genetic characterization of melanomas. In comparison with the other frequent variants we have shown that ALM has some important differences which emphasize that it is a distinct entity more probably related to certain cancer susceptibility but unrelated to familial melanoma, tendency to developing nevus or sun exposure.