Clinical analysis and prognostic significance of haemophagocytic lymphohistiocytosis‐associated anaplastic large cell lymphoma in children

Haemophagocytic lymphohistiocytosis (HLH) has been rarely described in children treated for an anaplastic large‐cell lymphoma (ALCL). We evaluated the incidence, the clinical and histological characteristics and the prognosis of HLH associated‐ALCL. The medical, biological, cytological and histological data of patients treated for ALK‐positive ALCL in the paediatric department of a single institution between 1975 and 2008 were analysed and assessed for HLH according to diagnosis criteria of the Histiocyte Society. Data concerning a series of 50 consecutive children with ALCL were reviewed. HLH‐associated ALCL was observed in 12% of the patients. Lung involvement was significantly more frequent in HLH‐associated ALCL patients than in the group without HLH (P = 0·004), as well as central nervous system (CNS) and bone marrow involvement (P = 0·001 and P = 0·007 respectively). The histological subtype in children with HLH‐associated ALCL did not differ from that of the group without HLH. There was no significant difference between the two groups in 5‐year EFS and OS (P = 0·91 and P > 0·99 respectively). In conclusion, HLH is not rare in paediatric ALCL. Despite a high incidence of visceral, CNS and bone marrow involvement, HLH does not seem to exert a significant impact on outcome in children treated for ALCL.