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. B afzelii is the predominant pathophysiology, but may not be the exclusive, etiologic agent of ACA. Borrelia garinii, has also been detected.
The rash caused by ACA is most evident on the extremities or limbs beginning with an inflammatory stage with bluish red discoloration and cutaneous swelling and concluding several months or years later with an atrophic phase. Sclerotic skin plaques may also develop.
As ACA progresses the skin begins to wrinkle.
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.