Pathogenetic Implications of the Age at Time of Diagnosis and Skin Location for Acrodermatitis Chronica Atrophicans

BACKGROUND: The pathogenesis of acrodermatitis chronica atrophicans (ACA) is not well understood. OBJECTIVE: The purpose of this study was to gain a better understanding of ACA by utilizing a large data set of adult Slovenian patients with Lyme borreliosis. METHODS: The age of 590 ACA patients was compared with that of patients with other manifestations of Lyme borreliosis. The location of the ACA lesion on the body was compared with that of erythema migrans (EM). RESULTS: Patients diagnosed with ACA were on average 14.3 years older than patients with EM (p\u3c0.001). ACA patients were also significantly older than patients with Lyme neuroborreliosis or Lyme arthritis (p\u3c0.001). The average delay in diagnosis of ACA was 1.6 years (range 0.1-20 years). For 572 (96.9%) of the ACA patients, the site of the skin lesion(s) was confined to an extremity vs. 79.6% for patients with EM, p\u3c0.001. For the 20 ACA patients who reported a preceding untreated EM lesion at the same body site, the mean time between the development of the EM and the onset of ACA was 3.0+/-4.4 (median 1.3, range 0.1-15.0) years. CONCLUSIONS: ACA is more likely to be diagnosed in older individuals than any other manifestation of Lyme borreliosis. ACA is more likely than EM to be localized anatomically to the extremities. Available data favor the hypothesis that ACA occurs most often on the extremities of older individuals because of predisposing age-related anatomic or physiologic changes, but more data are needed to define the latency period and other aspects of the pathogenesis of this skin condition