Disseminated superficial actinic porokeratosis treated effectively with topical imiquimod 5% cream

A 68-year-old man presented with a 3-year history of asymptomatic red marks on his limbs. On physical examination, he was found to have numerous circular, erythematous macules with a fine peripheral rim of scale on his upper arms and legs. A clinical diagnosis of disseminated superficial actinic porokeratosis (DSAP) was made. On histopathological examination of the lesional skin on the hands, an angulated parakeratotic tier was seen extending up through the epidermis. The patient was offered a trial of topical imiquimod 5% cream. He was instructed to apply it five times weekly for 6 weeks to the right forearm. This produced a dramatic inflammatory response with painful superficial ulceration of the affected skin after 4 weeks. At follow-up a further 4 weeks later, the treated areas were noted to have healed with slight superficial scarring and residual erythema, but no evidence of the original condition. DSAP is a disorder affecting areas exposed to sunlight, appearing mainly on the distal surfaces of the limbs. Treatment of DSAP is often difficult. Therapies such as cryotherapy with liquid nitrogen or use of topical 5-fluorouracil cream are generally either impractical or unsuccessful. Topical imiquimod 5% cream may prove to be a useful treatment option for DSAP. Our limited experience suggests that treatment should be introduced cautiously to avoid excessive inflammation. Further study is needed to confirm whether imiquimod should have a place in the management of DSAP.