Linear psoriasis with porokeratotic eccrine ostial and dermal duct nevus

Linear psoriasis is an uncommon form of psoriasis characterized by the linear distribution of the psoriatic lesions. It usually follows the lines of Blaschko with unilateral involvement. Poro keratotic eccrine ostial and dermal duct (PEODD) nevus is another rare dermatosis that follows Blaschko's line. The pathogenesis of linear psoriasis and PEODD nevus is unclear, but both could be best explained by a specific somatic mutation. Hence, it has been suggested that the mutation responsible for PEODD nevus would constitute a rare but critical psoriasis gene. In the literature, 1 case of linear psoriasis with PEODD nevus was reported, which may support this suggestion. This article describes another case of linear psoriasis and PEODD nevus. A 7-year-old boy had a 4-month history of multiple psoriasiform plaques, arranged in linear distribution, and had congenital linear hyperkeratotic papules and pits on the right side of his trunk and right arm.