Annular erythema of infancy

Annular erythema of infancy (AEI) consists of self-limited eruptions of erythematous, annular to polycyclic patches and plaques. It is an idiopathic figurate erythema. Over several days, a single lesion disappears without leaving behind any scale or hyperpigmentation. Mostly affecting the trunk, face, and extremities, this rash has no symptoms. The diagnosis of AEI is made through a combination of histopathologic and clinical examinations. The disease first manifests in infancy, and if treatment is not received, the periodic eruptions usually stop after the first year of life.

Signs and symptoms
Urticarial papules or slowly growing, raised-bordered annular or circinate erythematous plaques are found upon physical examination. Lesions are located on the face, trunk, and extremities, and the condition is asymptomatic. Individual lesions heal in a few days however, new ones keep coming up until the skin fully clears up, which happens at about a year of age. At that point, the skin looks completely normal.

Causes
Although the exact cause of AEI is unknown, a hypersensitivity reaction to an unidentified antigen is believed to be involved.

Diagnosis
Histologic findings include perivascular lymphocyte infiltrates and either neutrophils or eosinophils; they are nonspecific.