Hypopigmented lesions admixed with verrucous papules in a child with epidermolytic verrucous epidermal nevus

A female infant presented with asymptomatic hyperpigmented and hypopigmented verrucous papules and plaques along Blaschko’s lines on the right side of her body, with an absence of blistering, flexural accentuation or family history. A systemic examination was normal. Differentials considered were epidermal nevus, incontinentia pigmenti stage 2, lichen striatus, inflammatory linear verrucous epidermal nevus and linear epidermolytic ichthyosis (EI). A skin biopsy revealed epidermolytic hyperkeratosis (EHK). Mutation analysis could not be done as the parents were unwilling. EHK is classically seen in EI, which presents with marked blistering that resolves within a few months with hyperkeratosis; there is also accentuation around the flexures. Mosaic epidermolytic ichthyosis (mEI), a rare variant, is localised or along Blaschko’s lines, as in our patient. It differs from classic EI with the absence of blistering, flexural involvement and erythroderma. Epidermolytic verrucous epidermal nevus (VEN) and mEI refer to the same condition. Approximately 5% of all cases of VEN show the histological finding of EHK. Mosaic EI represents a somatic mutation of the KRT1 and/or KRT10 genes. Evaluation for this is important as mosaic conditions may lead to full-blown EI in the offspring of affected individuals. This case is being reported due to the unusual presentation of mEI as hypopigmented with hyperpigmented lesions and also to stress the importance of biopsy when a child presents with blaschkoid lesions.