Background–Hemophagocytic lymphohistiocytosis (HLH) is being increasingly reported as a complication of dengue. We present four cases of dengue associated HLH diagnosed in our hospital during the dengue outbreak of 2018. All the cases were treated with a short course of steroids (Dexamethasone) for 8 weeks, initially intravenous followed by oral, when the fever subsided along with supportive measures, and showed an excellent response. Diagnosis of HLH is challenging and usually missed as clinical and laboratory findings are nonspecific.

Aim and objective– The aim was to study the prevalence of secondary HLH in dengue fever.

Methods– Retrospective case record review was performed in patients of dengue fever with secondary HLH admitted in Hindu Rao Hospital, Delhi over a period of five months (July 2018 to November 2018). Dengue patients having fever for more than 7 days with HLH diagnosed based on Histiocytic Society 2004 protocol were enrolled for the study.

Results– Total 217 dengue serology (NS1/ IgM) positive patients of < 12 years of age were admitted over the period of 5 months (July to November 2018). Of the total number of cases, Four patients aged between 5 –12 years were diagnosed as a case of HLH, of which two  were females. The mean duration of diagnosis of HLH was 6 days (range 5 to 7 days) after admission and the mean duration of fever at the time of diagnosis was 17.5 days (range 14–21 days). All four children had splenomegaly, edema, ascites, pancytopenia, elevated liver enzymes, raised ferritin (>500 ug/L), Hypertriglyceridemia (>265 mg/dl) and three had bone marrow evidence of haemophagocytic activity. Lymphadenopathy was observed in 25 %. Central nervous system involvement was seen in 25%. All four children received dexamethasone for a period of eight weeks. All children showed clinical recovery in the form of disappearance of fever within 48 hours of start of Dexamethasone and got discharged eventually. 

Conclusion– HLH is a known complication of severe dengue infection. High degree of suspicion is needed to diagnose HLH early especially if there is ongoing fever of >7 days, persistent thrombocytopenia and leukocytopenia. Dexamethasone is effective in treating HLH secondary to Dengue