Performance of HScore in Reactive Hemophagocytic Lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a life threatening systemic hyperinflammatory disorder that leads to multiple organ damage. The most widely used diagnostic guidelines are the HLH 2004 guidelines proposed by the Histiocyte society. Recently, Fardet et al. has proposed a Scoring system, "HScore" for diagnosis of reactive HLH. To test the performance of "HScore" in diagnosis of reactive HLH and compare the credibility of the same with the existing gold standard 2004 guidelines in a cohort of Indian patients. This was a descriptive study of cases referred to the department of Pathology for bone marrow examination with suspicion or diagnosis of HLH from Jan 2015 to June 2017. The clinical records of these patients were analysed and diagnosed as positive and negative for HLH using the HLH 2004 guidelines and HScore, the scoring system developed by Fardet et al. Fifty cases fulfilled the inclusion criteria. The variables fever, hepato and /or splenomegaly, high triglyceride levels and marrow hemophagocytosis are highly significant to predict an individuals risk of HLH. We propose a cut-off of ≥ 166 for the diagnosis of HLH by using HScore. If 4 of the 7 criteria are fulfilled by HLH 2004 guidelines, there is an 80% probability of having HLH by HScore. The HScore is less restrictive in confirming a diagnosis of HLH compared to the HLH 2004 guidelines. HScore is a simple, and cost effective tool for diagnosis of reactive HLH. The higher the HScore, more is the probability of HLH.