Disseminated Superficial Actinic Porokeratosis

Disseminated superficial actinic porokeratosis (DSAP) is a skin condition that causes dry, scaly patches. Symptoms include a large number of small, brownish patches with a distinctive border, found most commonly on sun-exposed areas of the skin (particularly the lower arms and legs). DSAP usually starts during the third or fourth decade of life and rarely affects children. Lesions generally are more prominent in the summer and less prominent in the winter. While DSAP is usually not cancerous, squamous cell carcinoma or Bowen’s disease may occasionally develop within patches. DSAP may be inherited in an autosomal dominant matter or may occur in people with no family history of DSAP. Some cases are caused by a change (variant) in the MVK or SART3 genes. There is no standard treatment for DSAP, and treatment is generally not effective long-term. Sun avoidance may reduce the development of new patches. Treatments that have been beneficial in some people include topical imiquimod cream, topical 5-fluorouracil, and topical vitamin D analogs such as tacalcitol and calcipotriol. A newer therapy that has been successful is topical cholesterol/lovastatin. Other therapies that have been tested with varying results include cryotherapy, electrodessication (using electrical currents to remove patches), laser ablation, and photodynamic therapy.