Juxta-articular fibrotic nodules in Borrelia infection-ultrastructural details of therapy-induced regression

Abstract

Juxta-articular fibrotic nodules in chronic Borrelia burgdorferi infection commonly regress rapidly under antibiotic therapy. They may therefore serve as a good in vivo model for studying the development and regression of cutaneous fibrotic processes. As shown in a typical case of acrodermatitis chronica atrophicans, this spirochete-induced fibrosis in the upper subcutis of the elbow region is histologically characterized by broad hyalinized collagen tracts interspersed with prominent perivascular lymphocytes and plasma cells. These immune cells vanish completely after 5 days of antibiotic treatment, while fibroblasts discharge matrix vesicles and form elastic fibres.