Circumscribed palmar or plantar hypokeratosis: first report on a nonacral site with unique histologic features.

Circumscribed palmar or plantar hypokeratosis was first described by Pérez et al in 2002 as a unique entity of the skin in which they reported 10 patients who presented with well-circumscribed areas of erythematous depressed or eroded skin mostly over the thenar or hypothenar eminences of the palms and less commonly on the soles. Histologically, the lesions demonstrated an abrupt drop-off in the cornified layer resulting in a broad area of hypokeratosis. Pérez et al hypothesized that these lesions were a distinctive epidermal malformation. There have been several reports since, some of which implicate trauma as an etiologic agent; however, the exact etiology remains unclear. The authors present the first case of circumscribed palmar or plantar hypokeratosis on a nonacral site (chest of a 63-year-old man) with novel histological features, including granular parakeratosis and evidence of trauma (subepidermal fibrin and ulcerations).