Dengue Fever Associated Secondary Haemophagocytic Lymphohistiocytosis in an Adolescent with Beta Thalassaemia Trait: A Case Report

Dengue-associated Haemophagocytic Lymphohistiocytosis (HLH) is a rare but life-threatening hyperinflammatory complication. It arises when an exaggerated immune response is triggered by viral infection, leading to multi-organ involvement and high morbidity. Early identification and judicious management are critical for favourable outcomes. A 14-year-old boy presented with the dengueassociated secondary HLH, confirmed by fulfilling five of the eight HLH 2004 diagnostic criteria, including fever, splenomegaly, cytopenia, hyperferritinaemia, and hypofibrinogenaemia. The patient also carried beta thalassaemia trait, contributing to his anaemia, though it was incidental to the acute presentation. Management with broad-spectrum antibiotics (cephalosporin, followed by piperacillin-tazobactam) and supportive care led to prompt resolution, without immunosuppressive or HLH-specific therapy. Clinical improvement occurred within 48 hours, and sustained resolution was confirmed at one-week follow-up. This case supports the notion that, in selected dengue-associated HLH patients, especially those showing early clinical improvement, aggressive immunosuppressive therapy may be deferred. It emphasises the need for early suspicion, exclusion of differential diagnoses, and careful monitoring. The incidental beta thalassaemia trait, while unrelated to HLH pathogenesis, underscores the importance of genetic counselling. An extended follow-up validated complete recovery without complications. In dengue-associated HLH, prompt supportive and antibiotic therapy may suffice in certain cases, avoiding unnecessary immunosuppression. Clinicians should consider case-by-case management, guided by response trajectory and diagnostic completeness.