title: A case of chronic myeloproliferative syndrome followed by precursor T-cell acute lymphoblastic leukemia.
abstract: Interlineage switch from myeloid to lymphatic malignancies is a rare phenomenon. Progression from a BCR-ABL negative chronic myeloproliferative disorder (CMPD) to acute lymphoblastic leukemia (ALL) has been reported in very few cases. We describe the case of a 62-year-old man who developed precursor T-cell (pre-T) ALL 18 months after the diagnosis of an unclassifiable chronic myeloproliferative syndrome (CMPD, U), which had been treated with hydroxyurea (HU) over 12 months. The transformation from CMPD to pre-T-ALL was accompanied by clonal evolution from normal to a high hyperdiploid karyotype with an i(17q): 52,XY,+X,+2,+13,+14,+15,i(17)(q10),+19. Diverse pathways should be considered in this transformation process: although therapeutic induction of ALL is extremely rare and no MLL/11q23 rearrangement was detected by chromosome banding analyses and interphase fluorescence in situ hybridization (FISH), T-lineage ALL might have been caused by HU therapy for the CMPD. Chance coincidence of both disorders seems improbable, given the short interval from the diagnosis of the CMPD to the development of the pre-T-ALL, but nonetheless must be considered. A third explanation might be provided by a spontaneous interlineage switch, which would give further support to the theory that the CMPDs are disorders of a pluripotent stem cell. Interlineage switch might result from an aberrant differentiation of the malignant clone or from selection within a mixed population.
authors.affiliation: Bone Marrow Transplant Unit, University Hospital of Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany. ubacher@uke.uni-hamburg.de
authors.forename: Ulrike
authors.initials: U
authors.lastname: Bacher
authors.forename: Torsten
authors.initials: T
authors.lastname: Haferlach
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kern
authors.forename: Hans-Detlev
authors.initials: HD
authors.lastname: Harich
authors.forename: Susanne
authors.initials: S
authors.lastname: Schnittger
authors.forename: Claudia
authors.initials: C
authors.lastname: Haferlach
mesh_terms: D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D020223:Chromosome Painting; D018450:Disease Progression; D006801:Humans; D006918:Hydroxyurea / Q000627:therapeutic use; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D009196:Myeloproliferative Disorders / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000627:therapeutic use; D054218:Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics / Q000473:pathology*; D013577:Syndrome
chemical_list: D019384:Nucleic Acid Synthesis Inhibitors; D006918:Hydroxyurea