Histiocytosis following T-acute lymphoblastic leukemia: A BFM study

The coincidence of T-cell acute lymphoblastic leukemia (T-ALL) and histiocytic disorders, including hemophagocytic lymphohistiocytosis (T-ALL HLH) and Langerhans cell histiocytosis (T-ALL LCH), is very seldom and is usually associated with a dismal prognosis. Retrospective statistical analysis of all T-ALL patients, who have been registered in the BFM-ALL trials from 1981 - 2001 and who have subsequently developed a LCH HLH, in order to identify any common risk factors pre-disposing to the synchronous occurrence of both disorders. Six out of 971 T-ALL patients had either HLH or LCH ( 0.03% of treated T-ALL year). The mean age at diagnosis of T-ALL HLH LCH was significantly lower than in the remaining T-ALL group (4.05 ± 0.59 vs 8.82 ± 0.14 years; p = 0.000). The mean initial leukocyte count was higher than in the non-HLH LCH group (270 700 ± 60 677 μl−1 vs 134 141 ± 5663 μl−1; p = 0.074). No hemophagocytosis was seen in the initial bone marrow (BM) smears. Five of 6 patients obtained a good prednisone response (GPR) at day 8 in peripheral blood with