Differences by Anatomical Site of Non-Acral Lentiginous Melanomas of the Lower Limb

Background: Acral location of melanomas is associated with poor survival. It can be due, at least in part, to the fact that acral lentiginous melanoma, a distinct melanoma subtype, has a particular biological profile and a bad clinical behavior. However, since almost 50% of acral melanomas are not of acral lentiginous melanoma subtype, the worse clinical behavior could also be attributable to the intrinsic characteristics of the location.

Objective: This study aimed to investigate if melanomas of the lower limb excluding acral lentiginous melanoma differ by location.

Methods: This retrospective, observational study recruited patients from an oncology referral center in Spain. We included 285 patients with superficial spreading and nodular melanomas of the lower limb. We compare melanomas by site, clinical and pathological characteristics, and the differences by location of disease-free and melanoma-specific survival by the Kaplan-Meier method and Cox proportional hazard method.

Results: Patients with melanomas on the foot, compared to those on the rest of the limb, were older and reported having suffered less sunburns; the melanoma more frequently appeared in areas that had been rarely sun exposed, were more frequently of nodular type, presented thicker tumors, with more ulceration, less regression, and more advanced stage of the disease. Foot location increased the risk of relapse and decreased melanoma-specific survival.

Conclusion: Melanoma development in foot is less related to sun exposure and is associated with pathological features that can account for the worse prognosis and poorer survival.