Porokeratosis palmaris et plantaris disseminata or a disseminated late-onset variant of porokeratotic eccrine ostial and dermal ductal nevus (PEODDN) with follicular involvement.

A 48-year-old woman presented with a four-year history of pruritic, hyperkeratotic, spiny papules that began on her chest and spread to her extremities, groin, palms, face, and scalp where it caused non-scarring alopecia. Histopathologic features included cornoid lamella, which is the hallmark of porokeratosis. However, the patient's constellation of findings does not meet diagnostic criteria for any of the five clinical variants of porokeratosis. Her presentation is most compatible with either porokeratosis palmaris et plantaris disseminata (PPPD), which is a rare variant of punctate porokeratosis that can involve any area of the body or late-onset porokeratotic eccrine ostial and dermal ductal nevus (PEODDN), which is a rare, benign hamartoma of the eccrine sweat glands with porokeratotic histopathologic features that has been reported to occasionally have systemic involvement. Treatment of either condition is difficult although there have been reported successes with cryotherapy, surgical excision, and CO2 laser. Since porokeratosis is a disorder of keratinization and our patient has prominent follicular involvement, isotretinoin may be another reasonable therapeutic option.