Diagnosing and treating hemophagocytic lymphohistiocytosis in the tropics: systematic review from the Indian subcontinent.

BACKGROUND Hemophagocytic lymphohistiocytosis (HLH) is a catastrophic syndrome of unrestrained immune activation. Evaluation and management of HLH in the tropics is challenging. OBJECTIVES To examine the reported etiologies and management of HLH reported from the sub-continent. METHODS Systematic review of all published cases from the Indian sub-continent. RESULTS We found only 156 published cases of HLH from the sub-continent. HLH was reported from the immediate perinatal period to 46 years of age. Infection-associated HLH (IAHS) constituted 46.8% of all cases of HLH (44% and 51% in children and adults respectively). In adults, tropical infections triggered 51% of these cases of IAHS. Steroids were used in 47% of children and 10% of adults. Etoposide and/or cyclosporine were used in 8% children and 8% of adults only. Intravenous immunoglobulin was used in another 30% of children and 4% of the adults. HLH-related mortality occurred in 31.8% and 28% of children and adults respectively. CONCLUSIONS HLH is under-reported in the sub-continent and has high mortality. Cyclosporine and etoposide are seldom administered early despite diagnosis of HLH. Larger cohorts with IAHS triggered by tropical infections are urgently needed to understand its natural history and implications of this differing prescription pattern on mortality.