Erythema annulare centrifugum
What is erythema annulare centrifugum?
Erythema annulare centrifugum refers to a number of chronic annular (ring-shaped) and erythematous (red) skin eruptions. Other descriptive terms have been used to classify these types of lesions, including:
- Annular erythema
- Figurate erythema
- Erythema perstans
- Erythema gyratum perstans
- Erythema gyratum repens
- Erythema figuratum perstans
What are the signs and symptoms of erythema annulare centrifugum?
Erythema annulare centrifugum may occur at any time throughout life, from infancy to old age. The eruption usually begins as small raised pink-red spot that slowly enlarges and forms a ring shape while the central area flattens and clears. There may be an inner rim of scale. The rings enlarge at a rate of about 2–5 mm/day until they reach a diameter of about 6–8 cm. Sometimes the lesions do not form complete rings but grow into irregular shapes. One or several lesions may be present.
Erythema annulare centrifugum most often appears on the thighs and legs, but may occur on the face, trunk and arms. The lesions rarely cause symptoms but in some patients may cause mild itching or stinging.
What causes erythema annulare centrifugum?
Often no specific cause for erythema annulare centrifugum is found. However, it has been noted that erythema annulare centrifugum is sometimes linked to underlying diseases and conditions. These include:
- Bacterial, fungal and viral infections such as tuberculosis, sinusitis, candidiasis or tinea
- Drugs including chloroquine and hydroxychloroquine, oestrogen, penicillin and amitriptyline
- Cancer (especially the type known as erythema gyratum perstans, in which there are concentric and whirling rings)
- Food, most often blue cheese or tomatoes
- Recurrent or chronic appendicitis
- Cholestatic liver disease (blocked bile system)
- Graves disease (overactive thyroid gland)
In these situations, erythema annulare centrifugum resolves once the underlying cause is treated or the offending drug is stopped.
How is the diagnosis of annular erythema made?
The diagnosis of erythema annulare centrifugum is made clinically, and confirmed by histopathology showing perivascular lymphocytic infiltration.
Further investigations may be carried out to exclude other causes of annular rashes and to look for an underlying cause, if any.
Differential diagnosis includes:
- Erythema migrans (Lyme disease)
- Target lesions in erythema multiforme
- Annular plaques with central blisters in fixed drug eruption, bullous pemphigoid
- Serpiginous plaques in cutaneous larva migrans
- Annular dermal plaques in granuloma annulare, one form of lichen planus
- Annular scaly plaques in discoid eczema, chronic plaque psoriasis, seborrhoeic dermatitis, pityriasis rosea, discoid lupus, porokeratosis, tinea (dermatophyte infections)
- Annular smooth, urticated lesions in urticaria, Sweet syndrome, polymorphous light eruption, subacute cutaneous lupus erythematosus or systemic lupus erythematosus
What is the treatment of erythema annulare centrifugum?
Erythema annulare centrifugum usually clears up by itself. Eruptions may be last from anywhere between a few weeks to many years (the average duration is 11 months). Most cases require no treatment (and no curative therapy is known). However, topical corticosteroids may be helpful in reducing redness, swelling and itchiness.