# Disseminated Bartonellosis Masquerading as Autoimmune Glomerulonephritis: A Case Report

## TL;DR

A rare case of Bartonella henselae infection was mistaken for autoimmune disease, highlighting the need for careful diagnosis in complex cases.

## Contribution

This case report adds to the understanding of disseminated Bartonellosis mimicking autoimmune conditions in immunocompromised patients.

## Key findings

- Disseminated Bartonella henselae infection was initially misdiagnosed as autoimmune glomerulonephritis.
- Diagnosis was confirmed through serology and PCR of bone marrow after multiple investigations.
- The case underscores the importance of considering Bartonella in patients with atypical presentations and comorbidities.

## Abstract

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.

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.

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.