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.