Diagnostic Challenges in a Case of Hemophagocytic Lymphohistiocytosis Likely Induced by Coxiella burnetii

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of pathologic overactivation of the immune system that leads to excessive inflammation and tissue destruction. It can be genetic or acquired in the setting of infection, autoimmune disorders, or malignancy. Here we present a case report of a patient who was initially thought to have severe disseminated intravascular coagulation (DIC) but was ultimately diagnosed with HLH per the 2004 criteria, most likely secondary to <i>Coxiella</i> infection. A 69-year-old female presented with cough, acute hypoxic respiratory failure, and altered mental status. Laboratory findings were significant for coagulopathy initially thought to be DIC, but she was subsequently diagnosed with HLH. Bone marrow biopsy showed increased histiocytes showing hemophagocytosis. The trigger for the HLH was initially unclear, but the patient was eventually found to meet Q fever criteria after being found to be positive for <i>Coxiella</i>. She underwent treatment with the HLH-94 protocol, which includes high-dose steroids and etoposide with normalization of hematologic labs and resolution of symptoms. She was also treated with a standard course of doxycycline for <i>Coxiella</i>. HLH should be considered in patients who present with DIC-like labs and other hematologic abnormalities. In such cases, using the H score can assist in raising suspicion for reactive hemophagocytic syndrome. A biopsy of the involved site, such as bone marrow, showing increased hemophagocytosis can also help with confirming the diagnosis. It is important for early identification and initiation of treatment for HLH to improve survival outcomes.