Papular epidermal nevus with “skyline” basal cell layer (PENS)

BackgroundSeveral types of epidermal keratinocytic nevus are recognized.ObjectiveWe sought to describe a previously unreported keratinocytic nevus with distinctive clinical and histopathologic features in 5 patients.MethodsWe performed a clinical and photographic review, and obtained skin biopsy samples for histopathologic examination from each patient. Genetic analysis to screen for fibroblast growth factor receptor 3 and phosphatidylinositol 3-kinase, catalytic, alpha hotspot mutations was performed on lesional skin from two patients.ResultsFive infants (2 male, 3 female) had from 1 to 11 lesions present since birth. These consisted of 1- to 7-mm hyperkeratotic papules with a rough, flat surface and a round, commalike, rectangular, or polygonal shape. Histopathologic examination showed acanthosis with broad and rectangular rete ridges, and strikingly arranged basal cells with palisaded nuclei. Genetic testing on paraffin-embedded specimens from two patients ruled out hotspot mutations in the fibroblast growth factor receptor 3 and phosphatidylinositol 3-kinase, catalytic, alpha genes.LimitationsA small number of patients are presented.ConclusionWe propose the name “papular epidermal nevus with ‘skyline’ basal cell layer” (PENS) for this newly recognized condition.