[FGFR1-mutated B-cell acute lymphoblastic leukemia transforming to myelodysplastic / myeloproliferative neoplasm and acute myeloid leukemia].

A 77-year-old male with hyperleukocytosis and thrombocytopenia was diagnosed with Philadelphia chromosome (Ph) -negative B-cell acute lymphoblastic leukemia (ALL) ; he was treated with induction chemotherapy. Despite an initial complete remission, hyperleukocytosis was returned 18 months later. A bone marrow smear revealed a substantial increase in the number of myeloid cells with each stage of differentiation, which was markedly different from the initial presentation, resulting in the diagnosis of Ph-negative myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN). After a month, an autopsy revealed that the disease had progressed to acute myelogenous leukemia (AML). Since the first diagnosis, a chromosomal translocation, t (8;13) (p12;q12), was identified; this was subsequently confirmed by fluorescence in situ hybridization (FISH) analysis to comprise a genomic rearrangement of the fibroblast growth factor receptor 1 (FGFR1) gene. Collectively, this is a rare case of a myeloid/lymphoid neoplasm with an FGFR1 genomic rearrangement that initially presented as B-cell ALL, before developing into MDS/MPN and finally into AML. In the literature, although a transformation of MPN into ALL is often reported, the transformation of B-cell ALL into MPN is an infrequent event.