Will the Real Tinea Please Stand Up …
2. A man has had an asymptomatic rash for several weeks. Prior to its appearance, he was diagnosed with strep throat and treated with amoxicillin. The rash is quite striking: brightly erythematous, with annular margins on which the skin is red. But just behind the advancing margin is a parallel band of scaling.
Diagnosis: Erythema annulare centrifugum (EAC), one of the so-called “reactive erythemas,” which have several potential causes including streptococcal infections. The clinical picture and classic histologic pattern seen on biopsy effectively ruled out the other items in the differential diagnosis. EAC lesions can be large, appear in multiples, and spare only palms and soles. EAC is most often idiopathic. However, there are many reported triggers, including drugs (eg, gold, antimalarials, penicillin, and aspirin), infections (such as strep and dermatophytosis), and malignancies.
For more information on this case, see “Is A Common Illness The Cause of This Man's Rash?” Clin Rev. 2011;21(12).
