Retrospective single‐centre analysis of diagnostic approach to adult‐onset haemophagocytic lymphohistiocytosis

: Haemophagocytic lymphohistiocytosis (HLH) is rare disorder characterised by immune activation leading to cytokine storm and end-organ failure. It is associated with poor prognosis. HLH is predominantly a disease of early childhood, where it often results from genetic defects that impair cytotoxic function of natural killer cells and T cells. In adults, clinical manifestations are similar to those observed in children, although the aetiology is often unclear. We hypothesised that the poor prognosis is in part due to lack of awareness of the disorder, which results in incomplete investigation and failure to implement timely treatment. We evaluated diagnosis of HLH according to standard criteria in a single centre. In this retrospective case series, we present the clinical characteristics, treatment, and outcome of a cohort of adult-onset HLH identified in a tertiary hospital in Australia. In our cohort, hyperferritinaemia ≥10,000 μg/L was highly sensitive in detecting patients with adult-onset HLH, however the majority of patients who had hyperferritinaemia ≥10,000 μg/L did not have adult-onset HLH. We highlight that incomplete assessment of HLH criteria is frequently seen. Greater awareness of this rare disease and its diagnostic criteria may improve patient outcomes. This article is protected by copyright. All rights reserved.