Erythema migrans is a characteristic rash associated with which condition?

Erythema migrans is a distinctive, often bull's-eye-shaped rash that typically appears after a person is bitten by an infective tick carrying the bacterium Borrelia burgdorferi, which causes Lyme disease. This rash usually develops within a week or two after the bite and can expand over time. It is a hallmark sign of Lyme disease and is vital for its diagnosis, especially in cases where other symptoms may not yet be apparent.

The unique appearance of erythema migrans, characterized by a central clearing and an outer red ring, helps differentiate it from other dermatological conditions. In particular, psoriasis involves silvery scaly plaques, lupus erythematosus presents with a butterfly-shaped rash across the cheeks and nose, and scabies typically leads to intense itching and a rash due to the mite infestation, which appears differently than erythema migrans. These differentiating factors establish erythema migrans as a key indicator specifically associated with Lyme disease.