Annular Erythema of Infancy With Reactive Helper T Lymphocytes.

Annular erythemas of infancy (AEIs) are rare benign skin eruptions characterized by persistent, annular, urticarial, nonpruritic patches and plaques that develop in patients younger than 1 year. Histologically, a skin biopsy typically demonstrates a perivascular infiltrate in the dermis composed of small lymphocytes, neutrophils, and increased scattered eosinophils. We report a case of an AEI in an 11-month-old girl with uncommon histologic features. Recognition of these benign cells is important to avoid misdiagnosing them as atypical or neoplastic. We also provide a review of the differential diagnosis for AEIs.