Acrodermatitis chronica atrophicans
What is acrodermatitis chronica atrophicans?
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).
What causes acrodermatitis chronica atrophicans?
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.
Who gets acrodermatitis chronica atrophicans?
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.
What are the clinical features of acrodermatitis chronica atrophicans?
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.
- Inflammatory stage: ill-defined reddish discolouration and swelling of the affected area. The skin may be tender or painful.
- Atrophic stage: thin skin, loss of adnexal structures such as sweat glands and hair, disappearance of elastic fibres, and dilatation of blood vessels. Skin tears and ulcerates after minor trauma. The skin is described as tissue paper-like.
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.
Are there any systemic symptoms?
ACA is a symptom of the late stage of Lyme disease. Other features of late stage Lyme disease in patients with ACA include:
- Neurological symptoms—the most common
- Rheumatological symptoms
- Cardiovascular disease
What is the differential diagnosis of acrodermatitis chronica atrophicans?
ACA should be distinguished from:
- Venous insufficiency or Lipodermatosclerosis
- Thin skin due to ageing
- Lichen sclerosus
- Morphoea (localised scleroderma)
- Systemic sclerosis
How is the diagnosis of acrodermatitis chronica atrophicans made?
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).
How is acrodermatitis chronica atrophicans treated?
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.
Prevention of Lyme disease and acrodermatitis chronica atrophicans
- Avoid areas endemic for Lyme borreliosis.
- When walking in high grass or woodland, wear white clothes (so the tick can be seen more easily) with long sleeves, long trousers tucked into socks, or long boots.
- Use repellents/insecticides.
- After return from a walk in an endemic area, change your clothes and check your whole body carefully.
- The next day, check your body for ticks again.
- Remove the tick as a prompt removal decreases the risk of Lyme disease transmission. Disinfect the site. Use tweezers to carefully and steadily pull the tick out from the skin. Disinfect the site again. Wash your hands.
- Watch the site of the tick bite for several weeks. If a rash appears bigger than 5 cm or you have 'flu-like symptoms, consult your doctor.
There is no vaccine for Lyme disease.