Disseminated Superficial Actinic Porokeratosis
Disseminated superficial actinic porokeratosis (DSAP) is an inherited skin condition that causes red annular scaling lesions on the arms and legs. It usually affects fair skinned people over the age of 35, and it is more common in women than in men. About half of the children of those with DSAP will have this condition. The hallmark of these lesions is their subtle double edged scale. These may be confused with actinic keratoses which are precancerous lesions. Since people who have DSAP have had excessive sun exposure and are generally people with a fair complexion, it is important that they have an annual skin exam.
The lesions usually begin as a small scaly brownish-red spot which can expand to a diameter of 10mm. Sun exposure and sweating can contribute to worsening of the condition. Sun exposure causes more lesions and increased redness and itching. Sweating may contribute to itching and irritation. DSAP usually affects the areas with the most sun exposure predominantly the lower arms and legs.
Unfortunately, treatment of DSAP does not usually improve the condition dramatically. Creams can offer some slight help with cryotherapy also often being prescribed. Cryotherapy is when the lesions are removed by freezing them using liquid nitrogen, but this can sometimes lead to areas of hypo- or hyperpigmentation. Other treatments include topical fluorouracil, tretinoin, topical diclofenac, and topical vitamin D analogs. The best way to improve the condition is strict sun avoidance using sun protective clothing.