DERMATOLOGY FOR THE USMLE BENIGN SKIN DISORDERS (2) 2. DERMATOFIBROMA

DERMATOLOGY FOR THE USMLE

BENIGN SKIN DISORDERS (2)

2. DERMATOFIBROMA

→	General: Also known as fibrous histiocytoma, a common, benign dermal papule that occurs idiopathically or secondary to trauma such as a shaving or splinter injury, insect bite or ruptured cyst.
→	Clinical: Characterized by a single (or multiple), well-defined, firm and nontender papule or nodule. Lesions are usually smaller than 1 cm in diameter and vary in color from tan to brown The most common location is lower extremities but can occur anywhere. Dermatofibromas are usually asymptomatic, however, they may become irritated and pruritic. The classic feature is the “dimple sign ” The nodule dimples in the center when pinched
→	Diagnosis √ Best initial test: Clinical. √ Most accurate test: Skin biopsy showing fibrohistiocytic cell proliferation in the dermis with entrapment of collagen at the periphery.
→	Treatment √ First line: Reassurance. √ Second line: Surgical excision for symptomatic lesions or cosmetics.