Predictive factors of melanoma thickness

Melanoma thickness is a relevant prognostic marker that is crucial for staging and its calculation relies on the histopathological examination. There is a risk of thickness underestimation with an incisional biopsy if the latter is not performed on a tumor area where the thickness is maximal. This occurrence may have an impact on a therapeutic decision, particularly regarding the excision margins and the need for sentinel lymph node biopsy.

To assess the association between melanoma thickness and dermoscopic, demographic, epidemiological and clinical variables, aiming to identify predictive factors of thickness >1mm.

This was an observational and cross-sectional study, carried out on patients diagnosed with melanoma, from a single center over a time span of four years. Anatomopathological (thickness), dermoscopic, demographic, epidemiological, and clinical variables were collected. The associations between the variables with melanoma thickness were assessed.

A total of 119 patients were included. The presence of atypical vessels on the dermoscopic examination was an independent predictive factor of thickness >1mm. Conversely, an atypical reticular pattern predicted melanoma thickness <1mm. The presence of ephelides and a previous history of sunburn were also associated with melanomas thinner than 1mm in the univariate analysis.

The lack of data related to some variables and the absence of an optimal correlation between the dermoscopic and the anatomopathological examination constituted study limitations.

An atypical vascular pattern on dermoscopy is associated with thickness >1mm, helping with the choice of the optimal site to perform an incisional biopsy when an excisional biopsy is not feasible.