Which dermatologic finding is characteristic of dermatomyositis?

Which dermatologic finding is characteristic of dermatomyositis?

• A. Erythema nodosum
• B. Acanthosis nigricans
• C. Koebner phenomenon
• D. Gottron's sign

Answer: (D)

Dermatomyositis shows distinctive skin changes alongside proximal muscle weakness, and Gottron's sign is a classic manifestation. It appears as erythematous, sometimes scaly papules or plaques over the extensor surfaces of the hands, especially the knuckles (metacarpophalangeal and interphalangeal joints). This pattern on the extensor surfaces is highly characteristic of dermatomyositis and helps distinguish it from other skin conditions. Other options describe skin findings that are not typical for dermatomyositis: erythema nodosum are tender nodules usually on the shins; acanthosis nigricans is velvety hyperpigmentation in flexural areas associated with insulin resistance or malignancy; and Koebner phenomenon is new lesions at sites of trauma seen in diseases like psoriasis or lichen planus.

Dermatomyositis shows distinctive skin changes alongside proximal muscle weakness, and Gottron's sign is a classic manifestation. It appears as erythematous, sometimes scaly papules or plaques over the extensor surfaces of the hands, especially the knuckles (metacarpophalangeal and interphalangeal joints). This pattern on the extensor surfaces is highly characteristic of dermatomyositis and helps distinguish it from other skin conditions.

Other options describe skin findings that are not typical for dermatomyositis: erythema nodosum are tender nodules usually on the shins; acanthosis nigricans is velvety hyperpigmentation in flexural areas associated with insulin resistance or malignancy; and Koebner phenomenon is new lesions at sites of trauma seen in diseases like psoriasis or lichen planus.