Prognosis of polypoid melanoma: a comparative study with non-polypoid melanomas

Abstract

Polypoid melanoma is considered an exophytic and frequently non-pigmented variant of nodular melanoma with an adverse prognosis; however, very few studies have been published about it with contradictory results. Therefore, our objective was to determine the prognostic value of this configuration in melanomas. A transversal retrospective study of 724 cases was analyzed according to the main configuration (polypoid vs. non-polypoid) regarding their clinicopathologic characteristics and survival analysis. Of the 724 cases, 35 (4.8%) met the definition of polypoid melanoma; such cases, compared with non-polypoid melanomas, were associated with a high Breslow thickness (7 mm vs. 3 mm), 68.6% had a Breslow >4 mm; showed different clinical stages of presentation, and presented more ulceration (77.1 vs. 51.4%). In the 5-year overall survival (OS) analysis, polypoid melanoma is associated with a lower 5-year OS, together with lymph node metastasis, Breslow thickness, clinical stage, mitoses per mm², vertical growth phase, ulceration, and state of the surgical margins; however, in the multivariate analysis, the factors that remained independent predictors of death were the Breslow thickness groups, the clinical stage, the presence of ulceration, and the state of the surgical margins. Polypoid melanoma was not an independent predictor of OS. We found a prevalence of 4.8% of polypoid melanomas, which showed a worse prognosis than non-polypoid melanomas, explained by a higher proportion of ulcerated cases, greater Breslow thickness, and ulceration. However, polypoid melanoma was not an independent predictor of death.