Types of Seborrheic Keratosis
Dermatosis papulosa nigra is a term used to describe the seborrheic keratoses of the face seen more commonly in African-Americans. Dermatosis papulosa nigra lesions are 1 to 2 mm, dark brown keratotic papules concentrated around the eyes and upper cheeks, with an incidence of 30-35% in African-Americans.
Stucco keratoses, sometimes referred to as barnacles, are common, nearly inconspicuous, papular, warty lesions occurring on the lower legs, especially around the Achilles tendon area, the dorsum of the foot, and the forearms of the elderly. The 1- to 10-mm, round, very dry, stuck-on lesions are considered by most patients to be simply manifestations of dry skin. The dry surface scale is easily picked intact from the skin without bleeding, but it recurs shortly thereafter. The lesions can be removed with curettage or cryosurgery but are most often left untreated.
The sign of Leser-Treat is the sudden explosive onset of numerous seborrheic keratoses in association with internal malignancy. Most patients have metastatic disease when the keratoses appear. The SKs often parallel the course of the malignancy, decreasing in number and size following surgical or chemotherapeutic intervention and returning with recurrence of the cancer, but this is not always the case. Patients with numerous SKs need not be evaluated for malignancy unless the lesions erupt abruptly.