Epidermolysis bullosa nevus arising in a patient with Dowling-Meara type epidermolysis bullosa simplex with a novel K5 mutation

We report herein a 4-year-old girl with Dowling-Meara type epidermolysis bullosa (EB) who presented with peculiar pigmented nevi. Blister formation had repeatedly occurred on the erythematous plaques in a circinate fashion since birth, and marked hyperkeratosis was observed on the palms and soles associated with nail deformity. Her mother and maternal grandmother also had similar symptoms. In addition to the blistering lesions, the patient had three large, asymmetrical, pigmented plaques with color variegation. Light and electron microscopic findings of the blistering lesions showed a subepidermal blister with intracytoplasmic granules in keratinocytes as well as degeneration of basal cells and aggregation of tonofilaments. The pigmented lesions revealed histopathological features of compound nevus without malignant changes. Gene analysis revealed an E478K (Glu to Lys) mutation in exon 5 of the keratin 5 (K5) gene. These findings, together with clinical features, were consistent with those of Dowling-Meara type EB associated with so-called EB nevus.