Background Haemophagocytic lymphohistiocytosis (HLH) is an uncommon systemic inflammatory syndrome that can happen secondary to numerous conditions. It rarely occurs due to dengue infection causing significant mortality and morbidity even with appropriate treatment. The outcome is further poor if the diagnosis of HLH is delayed or left untreated. Therefore, a high degree of clinical suspicion is paramount in diagnosing HLH. Case presentation A 17-year-old Sinhalese boy was admitted to a tertiary care hospital in Sri Lanka with a 4-day history of fever, headache, nausea, vomiting, and diarrhea. He was hemodynamically stable, and the serological investigation confirmed a dengue infection. On the fifth day of fever, he entered the critical phase of dengue infection, confirmed by ultrasound evidence of plasma leaking. However, he had ongoing high fever spikes during the critical phase, and even after the critical phase was over, the fever spikes continued. Simultaneously, hepatosplenomegaly was noticed, and he showed persistent thrombocytopenia, neutropenia, and anemia despite the resolution of the critical phase. Further, the workup revealed a serum ferritin level of > 3000 ng/mL triglyceride level of 314 mg/dL, and the bone marrow biopsy revealed an increased haemophagocytic activity. Secondary HLH was diagnosed on the basis of criteria used in the HLH-2004 trial and successfully managed with intravenous dexamethasone 10 mg/body surface area/day for the first 2 weeks, followed by a tapering regimen over 8 weeks. Conclusion This case emphasizes the need to consider HLH as a potential complication when persistent fever and cytopenias are present after recovering from dengue fever, particularly in patients with unusual clinical features like hepatosplenomegaly. Early recognition and prompt treatment with appropriate immunosuppressive therapy, such as intravenous dexamethasone, can lead to a successful response and good prognosis.

Background Haemophagocytic Lymphohistiocytosis (HLH) is an uncommon systemic inflammatory clinical syndrome associated with numerous conditions and a rare complication of dengue associated with significant mortality and morbidity even with appropriate treatment. The outcome is further poor if the diagnosis is delayed or left untreated. Therefore a high degree of clinical suspicion is paramount in the diagnosis of HLH, especially in an atypical presentation of dengue infection. Case Presentation A 17-year-old boy with a non-significant past medical history admitted with a four-day history of fever, headache, nausea, vomiting, and loose stool. On admission, he was hemodynamically stable and managed as serologically confirmed dengue fever. On the 5th day of fever, he entered the critical phase, which was uncomplicated except for high fever spicks. Even after the critical phase was over, he had ongoing high fever spicks, hepatosplenomegaly with persistent thrombocytopenia, neutropenia and anaemia. Serum ferritin level was > 3000 ng/ml, while the triglyceride level was 314 mg/dl. Bone marrow biopsy revealed an increased haemophagocytic activity. Secondary HLH was diagnosed based on criteria used in the HLH-2004 trial and successfully managed with intravenous dexamethasone 10 mg/body surface area/day for the first two weeks followed by tapering of course over eight weeks. Conclusion Though this is a rare complication, the clinician must suspect HLH in expanded dengue syndrome complicated with ongoing fever, splenomegaly with cytopenias, and necessary investigations to establish a firm diagnosis. Early treatments will result in promising outcomes while preventing complications and reducing mortality.

The global prevalence of dengue cases has increased in India. The increasingly widespread distribution and the rising incidence of dengue virus infections are related to increased distribution of Aedes aegypti, an increasingly urban population, and increasing air travel. Several countries show that the age of the reported dengue cases has increased from 5-12 years, to older children and young adults. Although shock and plasma leakage seem to be more prevalent as age decreases, the frequency of internal hemorrhage rises as age increases. Increase in liver enzymes found in both children and adults indicated liver involvement during dengue infections. Pre-existing liver diseases in adults such as chronic hepatitis, alcoholic cirrhosis, and hemoglobinopathies may aggravate the liver impairment in dengue infection. Fulminant hepatitis is a rare but well described problem in adult patients with dengue infection. Currently, no specific therapeutic agent exists for dengue. The early recognition of dengue infection, bleeding tendency, and signs of circulatory collapse would reduce mortality rates in adult patients with dengue infection.