Erythema annulare centrifugum

Erythema annulare centrifugum (EAC) is a rare, chronic dermatological condition characterized by the presence of annular (ring-shaped) erythematous (red) lesions that expand centrifugally (outwardly) from a central point. The condition is often idiopathic, meaning its exact cause is unknown, but it can be associated with various underlying conditions.

Clinical Presentation

Erythema annulare centrifugum typically presents as red, ring-shaped lesions that may have a trailing scale at the inner border. These lesions can vary in size and may coalesce to form larger rings. The lesions are usually asymptomatic but can sometimes cause mild itching or burning.

Etiology

The exact cause of EAC is not well understood. It is considered to be a hypersensitivity reaction to various triggers, which may include:

• Infections (bacterial, fungal, or viral)
• Medications
• Autoimmune diseases
• Malignancies
• Food allergies

Diagnosis

The diagnosis of EAC is primarily clinical, based on the characteristic appearance of the lesions. A skin biopsy may be performed to confirm the diagnosis and rule out other conditions. Histopathological examination typically shows a perivascular lymphocytic infiltrate in the superficial and deep dermis.

Differential Diagnosis

Conditions that may resemble EAC and should be considered in the differential diagnosis include:

• Tinea corporis
• Granuloma annulare
• Erythema multiforme
• Nummular eczema
• Psoriasis

Treatment

Treatment of EAC focuses on addressing any underlying conditions and alleviating symptoms. Options may include:

• Topical corticosteroids
• Systemic antihistamines
• Identifying and eliminating potential triggers

Prognosis

The prognosis for EAC is generally good, with many cases resolving spontaneously. However, the condition can be chronic and recurrent in some individuals.

See Also

• Dermatology
• Hypersensitivity
• Skin biopsy