Dengue-associated secondary HLH in a pediatric patient: a rare case from Indonesia

Background. Hemophagocytic lymphohistiocytosis (HLH) is a potentially fatal condition characterized by excessive immune activation and severe systemic inflammation, often leading to multiorgan dysfunction. Secondary HLH (sHLH) may be triggered by infections, with the dengue virus increasingly recognized as a significant cause, particularly in tropical regions. Case report. We report a case of a 10-year-old girl who developed sHLH as a complication of dengue infection. She was referred to our hospital on the 13th day of fever, after resolution of bleeding manifestations but with persistent cytopenia following a six-day hospitalization. Serological testing revealed negative anti-dengue IgG and positive anti-dengue IgM. Five of the eight HLH-2004 diagnostic criteria were fulfilled: fever, splenomegaly, cytopenia affecting three cell lineages, hyperferritinemia, and hemophagocytosis confirmed by bone marrow examination. According to the Histiocyte Society (2004), initial therapy for sHLH typically includes corticosteroids, etoposide, and cyclosporine A; however, in this case, the patient showed marked clinical improvement with intravenous dexamethasone alone. Conclusions. Early recognition of dengue-associated sHLH is crucial to prevent severe complications and reduce mortality. This case underscores the importance of prompt diagnosis and timely therapeutic intervention.