The most characteristic skin symptom in Lyme-disease

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

Answer: (C)

The key idea is recognizing the expanding erythematous rash that appears at the site of a tick bite in early Lyme disease, classically called erythema migrans. This rash starts as red, enlarges steadily over days to weeks, and often develops central clearing, giving a ring or bull’s-eye appearance. It may be warm but is usually not painful, and systemic symptoms like fever or fatigue can accompany it. This expanding annular lesion is the hallmark skin finding of Lyme disease, distinguishing it from other skin conditions such as psoriasis (psoriatic plaques), erythema multiforme (target-like lesions), or pustular dermatitis. The term erythema chronicum migrans reflects this classic Lyme rash, making it the best answer.