Long-term involution of unilateral porokeratotic eccrine ostial and dermal duct naevus.

Sir, Porokeratotic eccrine ostial and dermal duct naevus (PEODDN) is a rare disorder of keratinization with eccrine involvement that histologically presents a cornoid lamella exclusively associated with eccrine ostia and the underlying sweat ducts (1). It is an expression of genetic mosaicism (2) and is characterized by asymptomatic grouped keratotic papules and plaques with a linear distribution, usually located on the acral portion of a limb (3). The lesions are congenital with a tendency to be stable and sometimes progressive.