Case report on Leptospirosis with Secondary Hemophagocytic Lymphohistiocytosis

Abstract

Leptospirosis is a zoonotic spirochetal infection with variable clinical manifestations and may mimic other tropical infections. Secondary hemophagocytic lymphohistiocytosis is a rare but potentially fatal hyperinflammatory complication. Early recognition is challenging because both conditions may present with fever, cytopenias, hepatic dysfunction, renal involvement, and systemic inflammation. Case presentation: A 22-year-old male presented with petechial and purpuric rash following occupational aquatic exposure during deep-sea diving training. Initial laboratory evaluation revealed severe thrombocytopenia, with a manual platelet count of 5 × 10⁹/L, and he was admitted to the medical intensive care unit with suspected immune thrombocytopenic purpura. During admission, he developed high-grade fever, worsening oxygen requirement, bilateral pulmonary infiltrates, anemia, neutrophilic leukocytosis, and circulatory shock requiring vasopressor support. Extensive infectious and autoimmune workup was negative. Markedly raised serum ferritin of approximately 4300 ng/mL, rising triglycerides, cytopenias, fever, and multiorgan involvement suggested secondary hemophagocytic lymphohistiocytosis. Initial leptospiral serology was equivocal; however, repeat IgM ELISA was positive, confirming leptospirosis. The patient received supportive intensive care, platelet and blood transfusions, corticosteroids, plasmapheresis, broad antimicrobial therapy, and doxycycline after confirmation of leptospirosis. His clinical status improved with recovery of platelet count, resolution of active bleeding risk, improvement in liver and renal parameters, and reduction in ferritin levels to 237 ng/mL. He was discharged ambulatory and clinically stable without oxygen or vasopressor support. Conclusion: This case highlights leptospirosis as a rare trigger of secondary hemophagocytic lymphohistiocytosis. In patients with unexplained febrile cytopenia and relevant environmental or occupational exposure, repeat leptospiral testing should be considered when initial results are inconclusive. Prompt antimicrobial therapy, immunomodulatory treatment, and intensive supportive care may improve outcomes.