Hemophagocytic lymphohistiocytosis with granulomatosis revealing a cat scratch disease in an immunocompetent adult: a case report and mini review

We report a case of hemophagocytic lymphohistiocytosis [HLH] triggered by Bartonella henselae , a gram-negative bacterium classically associated with cat-scratch disease. The patient was a 22-year-old immunocompetent male whose condition was initially misdiagnosed as tuberculosis and ultimately identified through clinical metagenomic sequencing. We also present the first focused review of Bartonella henselae –associated HLH, identifying only eight previously reported cases, the majority occurring in immunocompromised individuals. In addition, we analyse 16 cases in which infectious granulomatous diseases—including tularemia, leprosy, brucellosis, yersiniosis, coxiellosis, and actinomycosis—were initially misdiagnosed as tuberculosis. Finally, we examine the underlying factors contributing to these diagnostic errors, emphasizing the importance of epidemiological context and microbiological evidence in distinguishing Bartonella henselae infection and other granulomatous diseases from tuberculosis.