Disseminated Bartonellosis Masquerading as Autoimmune Glomerulonephritis: A Case Report

Background Although Bartonella henselae is primarily known for causing self‐limiting cat scratch disease in immunocompetent individuals, it can also lead to severe disseminated infections, particularly in immunocompromised patients. Case Presentation We present a rare case of disseminated B. henselae infection in a 70‐year‐old man with multiple comorbidities, including a recent aortic valve replacement and pacemaker implantation. The patient initially presented with purpuric skin lesions, progressive renal impairment, and pancytopenia, leading to a preliminary diagnosis of autoimmune glomerulonephritis and treatment with immunosuppressants. Subsequent investigations, including kidney and skin biopsies, revealed C3‐dominant glomerulonephritis and leukocytoclastic vasculitis, respectively. Further imaging uncovered a concurrent lung malignancy, treated with radiotherapy. Five months later, the patient presented with blood culture–negative endocarditis complicated by septic embolic strokes, persisting pancytopenia, and hepatosplenomegaly. Serology and B. henselae PCR of bone marrow confirmed disseminated Bartonella henselae infection. Conclusions This case highlights the diagnostic challenges of disseminated Bartonella infections, which can mimic autoimmune diseases and delay appropriate treatment. Clinicians should maintain a high index of suspicion to ensure timely diagnosis and management.