Acral lentiginous melanoma: who benefits from sentinel lymph node biopsy?

Background: There are significant clinicopathological, genetic, and biological differences between acral lentiginous melanoma (ALM) and other types of melanoma.
Objective: We sought to investigate the use of sentinel lymph node (SLN) biopsy for patients with ALM.
Methods: This was a retrospective review of 116 patients with primary ALM. Melanoma-specific and disease-free survival were estimated using the Kaplan-Meier method, together with multivariate analyses using the Cox proportional hazards regression model.
Results: All patients were Japanese (48 male and 68 female). Metastases in SLN were noted in 13 of 84 patients who underwent SLN biopsy. No patients with thin ALM (≤1 mm) and only 2 patients with nonulcerated ALM had tumor-positive SLN. Patients with positive SLN had significantly shorter melanoma-specific survival (5-year survival rate, 37.5% vs 84.3%; P < .0001) and disease-free survival (5-year survival, 37.5% vs 77.9%; P = .0024). Among patients with thick (>1 mm) ALM, the influence of SLN positivity on melanoma-specific survival was increased (5-year survival, 22.7% vs 80.8%; P = .0005).
Limitations: This was a retrospective study and had a small sample size.
Conclusions: SLN biopsy should be considered for patients with thick or ulcerated ALM. For patients with thin or nonulcerated ones, it may be of limited importance.
(Copyright © 2014 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)