A Case of Severe Dengue With Hemophagocytic Lymphohistiocytosis (HLH) Successfully Managed With Tocilizumab and Dexamethasone.

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening condition due to an uncontrolled hyperinflammatory response. While HLH can arise from various causes, it is most commonly triggered by infections. Dengue, a febrile viral illness prevalent in the tropics, can lead to HLH in rare cases. Dengue-associated HLH is particularly challenging to diagnose due to its clinical features overlapping with those of severe dengue. Unless immunosuppressive treatment is promptly initiated, the prognosis of dengue-associated HLH remains poor. A previously healthy 32-year-old female was admitted to a tertiary care hospital in Sri Lanka with high-grade intermittent fever, gastrointestinal symptoms, and severe dehydration. Initial blood investigations and a point-of-care ultrasound scan confirmed dengue hemorrhagic fever. Despite supportive therapy, the patient's condition deteriorated with persistent fever, severe bicytopenia, and liver impairment. She was diagnosed with HLH based on clinical and laboratory findings, including high ferritin levels and hemophagocytosis in the bone marrow. She was treated with intravenous dexamethasone and tocilizumab, leading to significant clinical improvement. Additionally, therapeutic plasma exchange was performed, contributing to recovery from severe liver dysfunction. This unique case highlights the importance of early recognition and integration of advanced immunosuppressive therapy in managing dengue-associated HLH. To the best of our knowledge, this is the first reported case where tocilizumab was successfully used in dengue-associated HLH, highlighting the potential of interleukin-6 (IL-6) receptor blockers in similar contexts. The coordinated efforts of hematology, gastroenterology, and general medical teams facilitated timely diagnosis and individualized management, demonstrating how interdisciplinary collaboration can enhance outcomes in complex cases.