Q fever, a rare cause of secondary hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare syndrome in which Coxiella burnetii is a very infrequent etiology. We present the case of a 62-year-old male with progressive pulmonary infiltrates, fever, hepatitis, and bicytopenia despite broad spectrum antibiotics. A thorough clinical evaluation led to a high suspicion of Coxiella burnetii infection, subsequently confirmed through a positive serum polymerase chain reaction (PCR) analysis. HLH diagnosis was established based on the fulfillment of 5/8 diagnostic criteria, obviating the need for a bone marrow biopsy. Targeted antibiotic treatment and dexamethasone led to full recovery within two weeks, eliminating the need for stronger immunosuppressive therapy.