Persistent Fever Despite Antitubercular Therapy: Unmasking Haemophagocytic Lymphohistiocytosis Triggered by Disseminated Tuberculosis

Haemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening condition that can complicate various infections, including <i>Mycobacterium tuberculosis</i> infection. We describe the diagnostic challenges encountered in a 37-year-old male from Nepal, who presented with dyspnoea and fever. Cross-sectional imaging showed disseminated tuberculosis (TB) with extrapulmonary manifestations. Persistent high-grade fever despite antitubercular treatment and empirical antibiotics, along with generalised lymphadenopathy and trilinear cytopenia, triggered further invasive investigations. Bone marrow aspirate showed haemophagocytosis, confirming HLH secondary to disseminated TB. The patient showed marked clinical improvement when intravenous corticosteroids were administered with antitubercular treatment. This case illustrates an uncommon presentation of a relatively common condition, and the importance of early consideration of HLH, especially in those with persistent unexplained high-grade fever and cytopenia.