Acrodermatitis Chronica atrophicans (ACA) is the third degree of European Lyme borreliosis. This particular progressive fibrosing skin manner is produced by an ongoing active infection with Borrelia afzelii. ACA is apparent on the extremities, especially on the extensor surfaces. It begins with an inflammatory degree distinguished by bluish-red discoloration and cutaneous swelling and concludes several months or years later with an atrophic phase. Sclerotic skin plaques may also occur. Physicians should practice serologic and histologic analyses to confirm this diagnosis. The option of treatment for ACA depends on the concurrence of other signs or symptoms of Lyme borreliosis. Appropriate consultations should be asked if extracutaneous signs and symptoms are present. ACA patients without concurrent extracutaneous disease do not need hospitalization.
Pathophysiology and Etiology
B afzelii is the principal etiologic agent of ACA but may not be the sole reason. Borrelia garinii, added genospecies of the Borrelia burgdorferi sensu lato (“in the broad sense”) complex, has also been identified in this setting.ACA is the only kind of Lyme borreliosis in which no spontaneous remission happens. Its pathophysiology is not yet completely understood. ACA appears to be linked with the long-term persistence of Borrelia organisms in the skin together with a specific immune response, which may provide to its manifestations.The tenacity of the spirochetes despite a marked cutaneous T-cell infiltration and high serum antibody titers may be correlated with the following factors:
Resistance of the pathogen to the whole system
- The pathogen’s strength to escape to immunologically protected sites (eg, endothelial cells, fibroblasts)
- The pathogen’s capacity to change antigens, which may lead to an inappropriate immune response
A limited pattern of cytokine expression in ACA, including reduction of interferon-gamma, may add to its chronicity. Cross-reactive antibody responses could take part in autoimmune damage, but whether autoimmune responses play any role in the pathogenesis of the disease is unclear. The pathogenic mechanism of atrophic skin changes also has not been explained. Conceivably periarticular regions are preferred sites because of reduced acral skin temperatures or reduced oxygen pressure. Lack of sufficient or appropriate treatment of early Lyme borreliosis facilitates the development of ACA.
The existence of ACA is related to the ecology of Lyme borreliosis, which modifies in different geographical regions of the world. The vectors of B afzelii, the principal etiologic agent of ACA are Ixodes ricinus, Ixodes hexagonus, and Ixodes persulcatus, which are disseminated in western and central Europe and in Asia. Most all of these hard tick species may also transmit B garinii, neurologic symptoms of Lyme borreliosis. Because the clinical diagnosis of ACA is much more complicated than that of erythema migrans. In fact, the ratio of erythema migrans cases may be higher than those already cited. The total number of circumstances could increase with the frequency of untreated European Lyme borreliosis rises. ACA is reasonably the most frequent late and chronic manifestation of the borreliosis seen in patients with Lyme disease.
The course of ACA is extended for as long as several years. It leads to boundless flaccid atrophy of the skin and to limitation of upper and lower limb joint mobility. Chronic, difficult-to-treat ulcerations of atrophic skin may occur after minor trauma. Bacterial superinfections may be observed. The general status of patients with ACA prevails good, though they may feel neurologic or rheumatologic signs and symptoms. As a practice, the result of treatment is good if the acute inflammatory stage of ACA is treated appropriately. The therapeutic outcome is hard to assess in patients with the chronic atrophic phase, in which many changes are only partially reversible. Although ACA rarely happens in childhood, its prognosis in pediatric patients is unknown. For this reason, it should be treated as early as possible to limit irreversible cutaneous damage.