Author: Dr Daniela Vanousova, Dermatologist, Czech Republic; Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, July 2015.
Acrodermatitis chronica atrophicans (ACA) is an uncommon skin condition affecting distal parts of the limbs. It is caused by chronic borrelial infection. It is the most common manifestation of the late stage of Lyme disease.
Acrodermatitis chronica atrophicans means persistent inflammation of the skin of the extremities with atrophy (tissue loss).
ACA is caused by ongoing active skin infection by the bacteria Borrelia afzelii, found mostly in Europe. These bacteria are transmitted by a tick bite several months or years before ACA develops.
ACA mostly affects middle-aged and elderly people, especially women. However, it can develop in anyone with untreated borrelial infection, including children. It is estimated that it arises in about 1–10% of people in Europe that have been infected with the Lyme disease bacteria.
ACA most often presents as an unilateral violet discolouration of the extensor parts of the upper or lower limbs, especially the dorsum of the hand, elbow, instep, ankle or knee. However, it can appear anywhere on the body, and can be bilateral.
ACA develops in 2 stages. Initial inflammation is followed by progressive fibrosis and cutaneous atrophy within several months or years.
Less common features of ACA include fibrous papules and plaques, and skin coloured nodules.
Most patients have history of tick bite. Some of them may recall a rash consistent with erythema migrans some months or years earlier, often affecting the same limb. Erythema migrans is a ring-like rash that occurs around the site of an borrelia-infected tick bite.
ACA is a symptom of the late stage of Lyme disease. Other features of late stage Lyme disease in patients with ACA include:
ACA should be distinguished from:
ACA is probably underdiagnosed. It is essential to obtain a detailed medical history and to determine whether there has been exposure to ticks (eg being in woody or grassy areas) or any previous manifestation of Lyme disease. When suspicious of ACA, a careful general skin examination should be carried out.
Borrelial serology in ACA shows positive high IgG level in enzyme-linked immunosorbent assay (ELISA) and on Western blot. IgG antibodies can persist long term, even after successful treatment for Lyme disease or ACA.
The presence of borrelial infection in the skin can be confirmed by polymerase chain reaction (PCR).
Depending on symptoms, patients with ACA may require referral to other specialists.
ACA is treated with antibiotics. The choice of antibiotic and length of the treatment depends on which other organs are involved and the severity of symptoms. Antibiotics used for ACA may include:
ACA is most effectively treated in the early inflammatory stage, when the skin changes are reversible. In the later atrophic stage, the infection can be eradicated, but skin changes persist.
There is no vaccine for Lyme disease.
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