Hemophagocytic Lymphohistiocytosis Secondary to Leptospirosis

Hemophagocytic lymphohistiocytosis (HLH) is an aggressive and life-threatening syndrome characterized by uncontrolled activation of lymphocytes and macrophages, leading to excessive cytokine secretion. It manifests with high fever, pancytopenia, hepatosplenomegaly, and liver dysfunction. While primarily observed in children with an incidence of 1/800,000 annually, it is suspected that many adults with unexplained severe illness and multiple organ failure may also have HLH. Primary HLH is genetic, whereas secondary HLH or hemophagocytic syndrome occurs secondary to conditions such as infections, autoimmune diseases, malignancies, or metabolic disorders. Leptospirosis, a significant zoonotic disease caused by Leptospira species, affects various mammals, with rodents being key reservoirs. In India, leptospirosis incidence has been rising, especially in the southern region. Secondary HLH due to leptospirosis is rare but notable. This report discusses an 18-year-old male with HLH secondary to leptospirosis. The patient presented with high-grade fever, gastrointestinal symptoms, and pancytopenia. Despite broad-spectrum antibiotics and supportive care, persistent cytopenias led to a bone marrow biopsy revealing hemophagocytosis. This case underscores the importance of recognizing HLH in the context of leptospirosis, especially given the rising incidence of the latter. Early diagnosis and appropriate management of HLH can significantly improve the outcomes. The patient responded well to targeted antibiotic therapy for leptospirosis.