skip to main content

Erythema migrans — USMLE Step 3 MCQ

Instant feedback + full explanation. One question, done properly.

ModerateAmbulatory Medicine / Primary CareErythema migransUSMLE Step 3

A 41-year-old hiker in Connecticut presents with an expanding annular rash on the thigh 10 days after a camping trip. He has malaise and arthralgia but no facial weakness or carditis symptoms. The lesion is 8 cm with central clearing. Vital signs are normal. Which of the following is the most appropriate next step in management?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Treat empirically with oral doxycycline

Erythema migrans is a clinical diagnosis and should be treated empirically; early serology can be negative.

Reference: IDSA/AAN/ACR Lyme disease guideline: https://www.idsociety.org/