What characterizes erythema marginatum associated with rheumatic fever?

Erythema marginatum, which can occur in rheumatic fever, is characterized by a non-pruritic, erythematous macular rash. This type of rash typically presents as pink or red spots that have clear borders and may appear on the trunk and proximal extremities. One distinctive feature of erythema marginatum is that it is not itchy, which sets it apart from other rashes that may provoke itching. The rash can also exhibit a wave-like pattern and may come and go over time.

Rheumatic fever itself is a complication of untreated streptococcal throat infection, and the presence of erythema marginatum is one of the important diagnostic criteria. Understanding this characteristic helps in identifying the condition and differentiating it from other types of dermatitis or skin reactions that may involve itching or chronic symptoms.