Aim Haemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening disorder. It can present to many specialities and individual Paediatricians are unlikely to develop significant experience of it. Early recognition and treatment improves the clinical outcome. The genetic basis of HLH is evolving and identification of viral triggers influencing management.

We aimed to study cases of HLH presenting to our tertiary Paediatric Hospital to identify the proportion of de novo cases and evaluate the role of Ebstein Barr virus (EBV) and genetic defects in the pathogenesis of HLH.

Methods Immunology, Rheumatology and Haematology Consultants identified children diagnosed with HLH over a 10 year period from 2003–2013. ICD10 codes were cross referenced. Case notes and electronic data were interrogated to extract relevant data.

Results 20 children were diagnosed with HLH over the 10 year period. Seven patients were de novo diagnoses and 13 had known haematological malignancy or rheumatological conditions.

At presentation, 15% met the HLH 2004 diagnostic criteria, rising to 45% at time of diagnosis (Figure 1).

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Abstract G461(P) Figure 1

Presenting specialities of children diagnosed with HLH

Viral triggers were investigated by EBV PCR and/or throat swab in 50% of patients and all de novo HLH patients were EBV positive. Of those found to be EBV positive, Rituximab was given to 4 patients. Genetic mutations were looked for in 40% of all patients (Figure 2).

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Abstract G461(P) Figure 2

Genetic studies in children with HLH

Nine patients recovered with standard management, 6 died and 5 proceeded to bone marrow transplant.

Conclusions HLH can present to a variety of paediatric specialities and a high index of suspicion is needed to make a timely diagnosis, as not all patients have ‘classical’ features at presentation. Identification of EBV gives the opportunity to use Rituximab effectively. In children with unusual responses to ubiquitous viruses, such as EBV, the competency of the host should be questioned. Some genetic defects predisposing to HLH in whom long term management with stem cell transplant can be curative are already known, and further defects may be discovered in the future. Accurate genetic diagnosis not only influences management, but is important for the families affected.