Porokeratotic eccrine ostial and dermal duct nevus showing partial remission by topical photodynamic therapy

Porokeratotic eccrine ostial and dermal duct nevus (PEODDN) is an uncommon, benign dermatosis and is characterized by asymptomatic grouped keratotic papules and plaques with a linear pattern on the extremities. Various treatments, including topical steroids, topical calcipotriol, topical 5-fluorouracil, retinoid, cryotherapy, and carbon dioxide laser ablation have been tried for PEODDN, but the results were unsatisfactory. Recently, topical photodynamic therapy (PDT) has been shown to be effective for various cutaneous disorders. We report a case of PEODDN showing partial remission with PDT using topical 5-aminolevulanic acid in a 4-year-old girl.