Chronic Brucella infection associated with amyloid light chain cardiac amyloidosis: a case report

Background: Amyloidosis is a rare group of diseases characterized by extracellular deposition of amyloid fibrils. The most common types are amyloid light chain (AL) and transthyretin (ATTR), while serum amyloid A (AA) type is relatively rare. Infections are often associated with AA amyloidosis, whereas AL amyloidosis typically results from abnormal proliferation of monoclonal plasma cells. However, the relationship between AL amyloidosis and infections remains unclear. Case presentation: We present the case of a 69-year-old male patient with chronic brucellosis complicated by heart failure. Laboratory tests showed significantly elevated myocardial enzymes and N-terminal pro-B type natriuretic peptide. Cardiac echocardiography and cardiac magnetic resonance imaging revealed abnormal myocardial hypertrophy, and the patient showed poor response to myocarditis-targeted treatment. Outcome: Genetic testing for inherited cardiomyopathies ruled out Fabry disease, hereditary hypertrophic cardiomyopathy, and ATTR amyloidosis-associated abnormal genes. Serum immunofixation electrophoresis indicated positivity for lambda light chain. AL cardiac amyloidosis was confirmed by myocardial biopsy. Conclusion: We report a case of chronic Brucella infection and AL-type cardiac amyloidosis, with a high overlap in clinical onset time. However, additional studies are needed to confirm the potential relationship between Brucella infection and AL-type cardiac amyloidosis.