Outcome of Viral-associated Hemophagocytic Lymphohistiocytosis at a Tertiary Hospital

Background: Little is known about viral-associated hemophagocytic lymphohistiocytosis HLH in Oman. This study was done to assess the epidemiology, clinical features and outcome of viral-associated HLH in our setting. Methods: We retrospectively reviewed children 0-18 years managed for viral-associated HLH at the Sultan Qaboos University Hospital, Oman, over a 15-year period 2006-2020. Patients' medical records were used to describe their demographic, clinical and laboratory features, management and outcome. Results: Fifty-six children were managed for HLH at Sultan Qaboos University Hospital over the last 15 years 2006-2020 of whom a third 19; 34% had a viral trigger. The median age at the time of diagnosis of viral-associated HLH was 83 13-96 months. Fever, cytopenia, hyperferritinemia and evidence of hemophagocytosis in bone marrow were the most consistent findings. Most of these children had either genetic predisposition to HLH 8/19; 42% or underlying immunodeficiency secondary to malignant conditions or chemotherapy/hematopoietic stem cell transplantation 6/19; 32%. Epstein-Barr virus 9; 47% followed by cytomegalovirus 6; 31% was the most common viral trigger in our setting. Treatment included antivirals 8; 42%, HLH 2004 protocol 4; 21%, rituximab 4; 21% and hematopoietic stem cell transplantation 3; 16%. Fourteen children 74% had full recovery. Conclusions: In our small cohort, viral-associated HLH was more frequently encountered in children with genetic predisposition to HLH or children with underlying immunodeficiency. In addition, we found that the outcome is overall good for children who have no genetic predisposition to HLH and children with genetic predisposition who underwent hematopoietic stem cell transplantation.