DERMATOLOGY FOR THE USMLE BENIGN SKIN DISORDERS (1) 1. KELOID

DERMATOLOGY FOR THE USMLE

BENIGN SKIN DISORDERS (1)

1. KELOID

→	General: Benign dense collagenous overgrowth that usually develops at the site of a healing skin injury. The uncontrolled collagen deposition results in vascular fibrous tissue extending beyond the borders of the original cutaneous injury (as opposed to hypertrophic scar; see below). High levels of transforming growth factor beta (TGF-β) are thought to contribute to the formation process. Keloids are prevalent in African Americans
→	Clinical: Characterized by a flesh-colored or hyperpigmented, smooth, firm and rubbery nodule or plaque with well-defined borders. Keloids commonly develop on the chest and ears but can appear almost anywhere. The size of keloids varies greatly; they can grow rapidly in days or develop gradually over months. The shape generally depends on the initial skin injury pattern, but commonly they are circular to oblong. Keloids are usually asymptomatic but may become irritated and pruritic.
→	Diagnosis → Best initial test: Clinical. → Most accurate test: Skin biopsy showing granulation tissue and dense dermal collagen arranged in a whorled or disorganized pattern
→	Treatment → First line: Intralesional steroids + avoid trauma (eg, earrings, cuts, etc). → Second line: Surgical excision (high rate of recurrence), radiotherapy, compression devices, cryotherapy, laser or occlusive silicone dressings.
→	USMLE Pearls: hypertrophic scar: This is also a benign dense collagenous deposition that occurs after healing of a cutaneous injury. It may be confused with a keloid. However, hypertrophic scars: → Do not extend beyond the margins of the original injury. → May spontaneously regress after months. → Have a more organized (parallel) pattern of dermal collagen deposition.