Erythema annulare centrifugum (EAC) is the most common of the major figurate erythemas, which also include erythema marginatum, erythema migrans, and erythema gyratum repens, being classified as a reactive erythema.1 It has been suggested that the epidermal spongiosis histologically represents a reaction to one of many antigens, of which could be infectious agents, drugs, Crohn's disease, pregnancy, autoimmune endocrinopathies, and occasionally, neoplasms.2 Lesions present first as firm pink papules that expand centrifugally and develop central clearing, then enlarge centrifugally again to form a large plaque.
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Calderon et al. (2024) studied this question.
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