Figurate erythemas - update and diagnostic approach.

Figurate erythemas (FE) represent an etiopathophysiologically heterogeneous group of diseases defined by their characteristic annular erythematous skin lesions. Diagnosis is made primarily by clinical examination together with histological findings; often it is a diagnosis made by exclusion. While some authors discuss FE as clinical reaction pattern rather than distinct clinical entities, others identify four classic FE: erythema annulare centrifugum, erythema gyratum repens, erythema migrans and erythema marginatum. The differential diagnoses of FE are numerous and often challenging. We therefore present a potential diagnostic algorithm for FE that discriminates the differentials according to their temporal evolution and the clinical/histological phenotype of the various subtypes. Since some FE may present with an underlying malignancy, diligent clinicians are needed when dealing with those entities.