DERMATOLOGY FOR THE USMLE BENIGN SKIN DISORDERS (3) 3. SEBORRHEIC KERATOSIS

DERMATOLOGY FOR THE USMLE

BENIGN SKIN DISORDERS (3)

3. SEBORRHEIC KERATOSIS

→	General: Also known as senile or brown warts, a benign pigmented tumor derived from epidermal cells. Seborrheic keratoses are the most common tumor in people older than 50 years. Lesions gradually increase in number with aging.
→	Clinical: Characterized by an asymptomatic, waxy, “stuck-on” appearing papule with a rough and irregular “greasy” surface. Seborrheic keratoses color varies from tan to brown or even black and some have irregular borders. With the exception of palms and soles, seborrheic keratosis can occur anywhere, though the most common locations are the extremities and trunk Patients may have from one to several dozen lesions and may rarely complain of pruritus.
→	Diagnosis √ Best initial test: Clinical. √ Most accurate test: Skin biopsy showing a papillomatous epidermis with thick basal layer and formation of keratin-filled “horn cysts.”
→	Treatment √ First line: Reassurance. √ Second line: Cryotherapy, curettage, laser or surgical excision for symptomatic lesions or cosmetics.
→	USMLE Pearls: Unevenly pigmented, black seborrheic keratoses with irregular borders can be clinically confused with malignant melanoma  If in doubt, perform an excisional biopsy with 1 to 3 mm margins to confirm the diagnosis.