Lyme borreliosis in medical practice: clinical mimicry and diagnostic errors

Background. Nowadays, Lyme disease has become a significant medical issue due to the polymorphism of its clinical manifestations. Physicians often settle on an entirely different final diagnosis. Therefore, analyzing clinical experience that can aid in improving the differential diagnosis of Lyme disease remains highly relevant. Purpose – to present and analyze clinical cases of confirmed Lyme disease that initially manifested with features resembling typical rheumatologic disorders. Materials and Methods. We analyzed and described four clinical cases of patients who were hospitalized at the Lviv Regional Clinical Hospital, taking into account general clinical assessment, laboratory testing, and instrumental diagnostic methods. Results. A series of clinical cases were analyzed, highlighting the challenges in the differential diagnosis of Lyme disease in clinical practice. In the first case, a 78-year-old female patient was hospitalized with typical vasculitic manifestations resembling Henoch–Schönlein purpura. Serological testing confirmed borreliosis, which allowed interpretation of the clinical picture as a secondary vasculitis of infectious origin – Lyme borreliosis. In the second case, the clinical presentation had been interpreted as spondyloarthropathy with sacroiliitis for over 10 years, with worsening over the last 3 years. A recalled tick bite temporally associated with the deterioration led to serological testing, revealing both IgM and IgG positivity for Borrelia burgdorferi. The third case involved a diagnostically complex course of inflammatory myopathy in an elderly patient. Positive IgG with negative IgM for Borrelia indicated a past i nfection without active chronic course. The fourth case demonstrated the diagnostic complexity of arthralgic syndrome in young patients. Despite the absence of classical features – such as erythema migrans or a known tick bite – positive IgM and IgG results confirmed a borrelial etiology of arthritis. Conclusions. Lyme disease can mimic a wide range of rheumatologic and other disorders, including reactive arthritis, spondyloarthropathies, IgA vasculitis, and polymyositis. Its diagnosis becomes especially challenging in the absence of a known tick bite. Given the nonspecific manifestations, the diagnostic work-up should include screening for Borrelia burgdorferi IgM and IgG. Timely diagnosis is essential for effective treatment and prevention of disease progression.