What is erythema annulare centrifugum?
Erythema annulare centrifugum is a chronic reactive form of annular erythema characterised by erythematous, circular, arciform, and polycyclic lesions, with a characteristic delicate scale behind the advancing edge (‘trailing scale’).
Erythema annulare centrifugum
Who gets erythema annulare centrifugum?
Erythema annulare centrifugum most often occurs in adults, but all ages can be affected. The average age of onset is 40 years .
What causes erythema annulare centrifugum?
Erythema annulare centrifugum has been shown to occur in association with underlying medical conditions and medications in 33–72% of cases [1,2]. It is thought to be a form of hypersensitivity reaction.
The most commonly associated conditions are:
- Cutaneous fungal infection (tinea pedis)
- Internal malignancy
- Adverse reaction to medications
- Haematological disorders
- Endocrine disorders
- Rheumatic disease.
Dietary causes of erythema annulare centrifugum include blue cheese and tomatoes. Stress has also been associated with the disease [1,3].
What are the clinical features of erythema annulare centrifugum?
Erythema annulare centrifugum typically affects the thighs, buttocks, and upper arms. However, any location on the body can be affected.
Erythema annulare centrifugum usually starts as a small pink papule that gradually enlarges over several weeks to form annular plaques with central clearing. These plaques can vary in size from a few millimetres to a few centimetres in size. Annular lesions can be partial (arciform) and coalesce to form polycyclic (ringed), serpiginous (wavy), and gyrate (revolving) patterns.
Classically, the annular or arciform lesions have an advancing outer erythematous edge with a trailing (inner) scaly edge. The rash may be itchy.
How is erythema annulare centrifugum diagnosed?
Erythema annulare centrifugum can sometimes be diagnosed on clinical features alone if the characteristic trailing scale is present. The diagnosis can be confirmed by skin biopsy in which the typical features of superficial or deep erythema annulare centrifugum are noted: a dense perivascular lymphocytic infiltrate involving either the superficial or deep vascular plexus, which is known as a ‘coat-sleeve’ appearance. Secondary changes to the epidermis may include spongiosis (inflammation of intercellular oedema), parakeratosis (disturbance in the keratinisation process), and hyperkeratosis (thickening of the outer layer of the epidermis) .
Investigations for an underlying cause should be guided by the patient's history and examination findings. An age- and symptom-appropriate cancer screening should be undertaken.
What is the differential diagnosis for erythema annulare centrifugum?
Several skin conditions should be considered in the differential diagnosis of erythema annulare centrifugum. Conditions to consider include other forms of annular erythema:
- Erythema perstans — a paraneoplastic eruption associated with underlying malignancy in which there are concentric and whirling rings
- Erythema gyratum repens — a paraneoplastic rash with a typical ‘wood-grain’ appearance from rapidly expanding erythematous lines in a concentric pattern
- Necrolytic migratory erythema — ring-shaped red rashes that blister, erode, and crust over time; this classically occurs with an underlying glucagonoma (a glucagon-producing tumour that develops in the Islets of Langerhans)
- Erythema marginatum — a rash occurring in acute rheumatic fever; this classically appears as pink or red macules or papules that spread outwards in a circular shape with a sharp border
- Erythema multiforme — targetoid lesions occurring on the backs of hands and tops of feet (but that may occur anywhere); lesions consist of sharply demarcated, reddish-pink macules that gradually enlarge to form plaques; the central part of the lesions changes colour or clears, creating rings
- Erythema migrans (the first stage of Lyme disease) — an expanding red patch of skin that starts at the site of a tick bite and gradually expands to reach several dozens of centimetres in size.
Other disorders to be considered include:
- Tinea (dermatophyte infection) — gradually enlarging, itchy, and scaly annular lesions with central clearing
- Granuloma annulare — an annular rash with a rubbery, raised, smooth erythematous edge with central clearing
- Erythema papulatum centrifugum — a sweat-related itchy condition where erythematous papules form enlarging annular and arciform structures on the trunk and limbs
- Secondary syphilis — this may present with non-itchy scaly annular and polycyclic plaques
- Cutaneous lupus erythematosus, especially subacute cutaneous lupus erythematosus and systemic lupus erythematosus.
What is the treatment for erythema annulare centrifugum?
It is essential to identify and treat the underlying cause of erythema annulare centrifugum where possible, such as a cutaneous fungal infection.
Topical medications that have been used to treat erythema annulare centrifugum include:
Systemic medications that have been used to treat the underlying cause of erythema annulare centrifugum include:
Etanercept  has been reported to induce remission in a case of widespread erythema annulare centrifugum.
What is the outcome for erythema annulare centrifugum?
Erythema annulare centrifugum tends to recur over several months or years, but it can spontaneously remit. Kim et al showed that 18.5% of affected individuals had persistent skin lesions for over 1 year and that the average duration of skin lesions was 4.7 months .