Acrodermatitis chronica atrophicans
Acrodermatitis chronica atrophicans (ACA) is a skin rash indicative of the third or late stage of European Lyme borreliosis. ACA is a dermatological condition that takes a chronically progressive course and finally leads to a widespread atrophy of the skin. Involvement of the peripheral nervous system is often observed, specifically polyneuropathy. This progressive skin process is due to the effect of continuing active infection with the spirochete "Borrelia afzelii", which is the predominant pathophysiology. "B. afzelii" may not be the exclusive etiologic agent of ACA; "Borrelia garinii" has also been detected. Presentation. The rash caused by ACA  is most evident on the extremities. It begins with an inflammatory stage with bluish red discoloration and cutaneous swelling, and concludes several months or years later with an atrophic phase. Sclerotic skin plaques may also develop.As ACA progresses the skin begins to wrinkle. Diagnosis. Generally a two-step approach is followed. First, a screening test involving IgM and IgG ELISA. If the first screening has a positive result, or there is a high clinical suspicion in spite of Elisa being negative, then the second step is to perform a Western Blot as a confirmatory test. Other methods include microscopy  and culture (in modified Kelly's medium) of skin biopsy or blood samples. Treatment. The course of ACA is long-standing, from a few to several years, and it leads to extensive atrophy of the skin and, in some patients, to the limitation of upper and lower limb joint mobility.The outlook is good if the acute inflammatory stage of ACA is treated adequately. The therapeutic outcome is difficult to assess in patients with the chronic atrophic phase, in which many changes are only partially reversible. Physicians should use serologic and histologic examination to confirm the diagnosis of ACA. Treatment  consists of antibiotics including doxycycline and penicillin for up to four weeks in the acute case. History. The first record of ACA was made in 1883 in Breslau, Germany, where a physician named Alfred Buchwald first delineated it.Herxheimer and Hartmann described it in 1902 as a "tissue paper like" cutaneous atrophy.