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Author: Dr Karen Koch, Dermatologist, Waikato Hospital, Hamilton, New Zealand. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. June 2019.
Erythema annulare centrifugum (EAC) is a chronic reactive form of annular erythema characterised by erythematous, circular, arciform and polycyclic lesions with characteristic delicate scale behind the advancing edge (‘trailing scale’).
Erythema annulare centrifugum most often occurs in adults, but all ages can be affected. The average age of onset is 40 years .
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:
Dietary causes of erythema annulare centrifugum include blue cheese and tomatoes. Stress has also been associated with the disease [1,3].
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 with central clearing, to form annular lesions over several weeks. These 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.
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 typical features of superficial or deep erythema annulare centrifugum are noted: ‘coat-sleeve’ dense perivascular lymphocytic infiltrate either involving the superficial or deep vascular plexus. 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 history and examination. Age and symptom-appropriate cancer screening should be done.
Several skin conditions should be considered in the differential diagnosis of erythema annulare centrifugum. Conditions to consider include other forms of annular erythema.
Other disorders to be considered include:
It is essential to identify and treat the underlying cause of erythema annulare centrifugum where possible, such as a cutaneous fungal infection.
Some medications that have been used to treat erythema annulare centrifugum include:
Erythema annulare centrifugum tends to recur over several months or years but can spontaneously remit. Kim et al. showed that 18.5% of affected individuals had persistent skin lesions for more than one year and that the average duration of skin lesions was 4.7 months .
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