Porokeratosis (DSAP)

Key Points
Most likely represents an inherited skin disorder due to abnormal sensitivity to the sun
Oval to round scaly reddish brown patches on arms and legs

Disseminated Superficial Actinic Porokeratosis (DSAP) is a genetic skin disorder that causes reddish brown scaly spots primarily on the arms and legs and, more frequently, on the lower legs of women. Half the children of affected parents will inherit the disorder. DSAP may not reveal itself, however, until an affected person been exposed to the sun a certain amount of accumulated time. Usually, it will reveal itself around the age of 35 to 40 and will increase in intensity as a person ages; this is particularly true of fair-skinned people. DSAP is more prominent in the summer, and may be triggered by the ultraviolet light of sun lamps.

The scaly spots will generally start small and grow over the life of the victim. The spots seem to grow or Itch after sun exposure. Sweating is absent within the lesions. It is considered by most practitioners to be a low grade, premalignant condition in which individual lesions very rarely degenerate into Squamous Cell Carcinoma.

Differential Diagnosis (Other conditions with similar appearance)
Solar keratosis
Seborrheic keratosis

Diagnosis
biopsy
visual examination

DSAP is usually apparent to a trained dermatologist. A skin biopsy may be taken to confirm the diagnosis.

Treatment
There is no cure
Limited sun exposure may slow the growth and prevent additional lesions

There is no treatment offering complete cure for DSAP. Creams such as Retin-A, Tazorac, Efudex and Aldara offer some help. Cryosurgery (freezing the lesions lightly) can be used to remove larger lesions. The best thing to do is to avoid sun exposure which may reduce the lesions. Wear long sleeves and pants and use high SPF sunscreens on the legs and arms. It may also be reasonable to have the lesions checked yearly by a trained professional to monitor for changes of Squamous Cell Carcinoma.