Lyme disease skin lesion hallmark.

• A. Psoriatic plaque
• B. Erythema exudativum multiforme
• C. Dermatitis pustulosa
• D. Erythema chronicum migrans

Answer: (D)

The main concept here is recognizing the classic skin manifestation of early Lyme disease. The hallmark is erythema migrans, an expanding red rash that appears at the site of the tick bite after a period of incubation. It often starts as a small so- or sun-shaped patch and gradually enlarges, frequently with central clearing giving a bull’s-eye appearance. This rash is characteristic of early localized Lyme and can be seen with or without mild systemic symptoms like fatigue or low-grade fever.

Other skin conditions listed don’t fit Lyme disease. A psoriatic plaque is a chronic, well-demarcated, silvery-scaled lesion typical of psoriasis. Erythema multiforme presents as target-like lesions often on the hands and feet and is usually linked to infections like HSV or certain drugs. Dermatitis pustulosa shows pustules on an erythematous base and is not typical of the Lyme rash.