Annually Recurring Erythema Annulare Centrifugum: A New Case
Annually recurring erythema annulare centrifugum (AR-EAC) is a rare variant, characterized by typical annular plaques recurring in the same period of the year. This report describes 5 new cases and present a review of the literature. Patients were 3 females and 2 males with an age range of 25–55 years. Multiple annular plaques were located at the thighs in 4 patients and the neck in one patient. In 1 patient, a single lesion was present.

Plaques were recurring in summer in 3 cases; in 1 case, in spring; and another patient, in winter since 3–4 years. Lesions were self-healing in few days or weeks. Histologically, the epidermis presented mild acanthosis with patchy spongiosis, slight parakeratosis, and mild exocytosis. There was a perivascular lympho-histiocytic infiltrate of variable intensity in the superficial dermis, with occasional eosinophils. In 1 case, the inflammatory infiltrate reached the deep dermis. Mucin deposition was absent.

Phenotyping studies in 1 case revealed a predominance of T cells, with a small B-cell component. Moreover, a moderate number of CD123<sup>+</sup> plasmacytoid dendritic cells and CD1a<sup>+</sup> dendritic cells were noted. Fourteen cases of AR-EAC have been published previously. Collectively, patients' age ranged from 16 to 83 years, with a mean age of 47 years and a disease duration of 1–30 years. Lesions affected more frequently extremities and recurred most commonly in summer.

Patients were all in good general health. Topical corticosteroids were the mainstay of treatment. AR-EAC is a benign disorder, the nature of which remains enigmatic.