Erosive pustular dermatosis (EPD) is a rare inflammatory disease of unknown etiology that usually occurs in elderly patients with lighter skin phototypes. There is a slight male predominance. Two types are described: EPD of the scalp and EPD of the legs. Clinical appearance, histology, and response to therapy of the lesions in those 2 sites are essentially identical, but the settings in which they occur differ remarkably. On the scalp, EPD invariably develops in areas of long-standing sun damage, whereas leg involvement occurs on non-sun-damaged skin of patients with chronic venous stasis.

The etiology of EPD remains unknown. However, it is claimed that the major predisposing condition is cutaneous atrophy, which is primarily the result of actinic damage on the scalp and stretching of the skin secondary to the edema of venous insufficiency on the legs. EPD then develops from one or more triggering factors, eg, physical, medical, or surgical trauma. Treatment of actinic keratosis on the scalp (including liquid nitrogen and topical chemotherapeutic agents), surgical procedures (such as neurosurgery, skin grafting, hair transplant, laser therapy, and radiation therapy), physical injury, and sunburn have all been reported as provoking factors in the development of EPD of the scalp. Similarly, compression therapy has been found to be an inciting factor for EPD of the legs.

EPD is clinically characterized by sterile pustules and chronic crusted erosions. Crusts resolve leaving atrophy and scarring alopecia, and new areas of pustulation develop within a few days. Often, the presence of crusted erosions or ulcers predominates, and pustules are not seen. Itch or mild to moderate pain may be noted.

EPD has rarely been seen in patients with autoimmune disorders such as rheumatoid arthritis, Hashimoto thyroiditis, autoimmune hepatitis, and Takayasu arteritis. The significance of this is unclear.

EPD has a chronic, recurring, and slow but progressive course. Scarring alopecia and cutaneous malignancies such as basal cell carcinoma and squamous cell carcinoma may eventuate in the scar tissue.