[Porokeratotic eccrine ostial and dermal duct naevus (PEODDN)]

The porokeratotic eccrine ostial and dermal duct naevus or PEODDN represents a very rare hamartoma of the eccrine sweat glands. A 16-year old boy had developed subtle hyperkeratotic skin lesions on his right hallux at six months of age. When he was eight years old, he developed similar lesions on his right palm. Clinically the lesions were coniform hyperkeratoses. The histopathological examination confirmed the diagnosis of a PEODDN showing typical cornoid lamella where the eccrine secretory ducts penetrated the epidermis. Although porokeratotic eccrine ostial and dermal duct naevi are generally considered as unresponsive to conservative treatment, in our patient topical treatment with tazarotene gel 0.1% resulted in a significant improvement within three weeks.