Erythema Annulare Centrifugum

Key Points
Skin condition which forms interesting circular patterns on the affected areas
Exact cause is unknown, but it likely represents a reactive condition to another inflammatory focus in the body
Consists of red, ring-like lesions with elevated borders which may be accompanied by scaling or mild itching

Erythema annulare centrifugum is a skin condition which typically affects the thighs and legs, but can develop on the torso, arms and face. The condition initially consists of a small, elevated spot which is pinkish red in color. Lesions grow slowly (up to 6-8 cm), clearing in the center and forming a ring-like, elevated border. It is often mistaken for ringworm clinically. Scaling may develop in flat central areas of lesions, and affected persons may experience mild itching. A “trailing scale” is often seen with EAC, with the advancing border being red and the inner aspect of the ring demonstrating the scale. This is a very useful diagnostic feature clinically.

The exact cause of Erythema annulare centrifugum is unknown. While it typically presents ideopathically, some cases may be related to underlying disorders, including infection, drug reactions, cancer, and food allergy.

Differential Diagnosis (Other conditions with similar appearance)

T-cell lymphoma
Erythema gyratum repens
Granuloma annulare
Subacute Cutaneous Lupus erythematosus

Diagnosis
Key Points
Diagnosis based on appearance of the affected area
Skin biopsy and other tests may be performed to confirm diagnosis and rule out other conditions

Erythema annulare centrifugum is typically diagnosed based on the appearance of the affected area. Skin biopsy and other tests may be performed to confirm the diagnosis and to rule out similar appearing conditions.

Treatment
Condition is typically self-resolving, thought it may persist for years
*When treatment is required, it typically consists of the application of topical steroids

Erythema annulare centrifugum does not usually require treatment, as the condition is self-resolving in most cases. The condition may persist for months or even years in some cases. When treatment is required, it typically consists of the application of topical steroids to the affected area to reduce symptoms. Given the fact that EAC can be associated with an underlying primary problem, a doctor will usually perform a review of systems and physical exam to look for such a disorder.