Retrospective Single-Centre Analysis of Diagnostic Approach to Adult-Onset Haemophagocytic Lymphohistiocytosis.

Background Haemophagocytic lymphohistiocytosis (HLH) is a rare disorder with a poor prognosis characterised by substantial immune activation leading to end-organ failure. In childhood, genetic defects that impair cytotoxic function of natural killer cells and T cells. (HLH) are often identified. In adults, clinical manifestations are similar to those observed in children but the aetiology is often unclear. Aims To evaluate whether poor prognosis for adult HLH is in part due to lack of awareness of the disorder, which results in incomplete investigation and failure to implement timely treatment. Methods We performed a retrospective case series of adult-onset HLH in a tertiary hospital in Australia. We evaluated clinical characteristics, treatment and outcome, and related these to application of standard diagnostic criteria for HLH. Results In our centre, incomplete assessment of HLH criteria was common. Serum ferritin was the criterion most commonly assessed. Hyperferritinaemia >= 10 000 mu g/L was highly sensitive in detecting patients with adult-onset HLH; however, the majority of patients who had hyperferritinaemia >= 10 000 mu g/L did not have adult-onset HLH. Conclusion The present study highlights the importance of comprehensive application of diagnostic criteria to improve accuracy and timelines of the diagnosis of adult onset HLH.