title: Mixed-lineage leukemia revisited: acute lymphocytic leukemia with myeloperoxidase-positive blasts by electron microscopy.
abstract: Seven adult patients with untreated acute lymphocytic leukemia (ALL) who manifested 5% to 40% myeloperoxidase (MPO)-positive blasts by electron microscopy (EM) are reported. Six patients had an L2 morphology, and one had an L1 morphology by the French-American-British (FAB) classification. The immunophenotype was T cell in four patients. Molecular analysis showed rearrangement of the immunoglobulin JH in four patients, three of them also having rearrangement of the T-cell receptor beta or gamma. Induction chemotherapy with vincristine-doxorubicin-dexamethasone (VAD) produced a complete remission in five of six patients (83%). Our findings suggest the existence of a previously undescribed subtype of mixed-lineage leukemia, which by morphology and immunophenotype often appears as T-cell ALL but exhibits MPO-positive blasts by EM.
authors.affiliation: Department of Hematology, University of Texas, M.D. Anderson Cancer Center, Houston 77030.
authors.forename: H M
authors.initials: HM
authors.lastname: Kantarjian
authors.forename: C
authors.initials: C
authors.lastname: Hirsch-Ginsberg
authors.forename: G
authors.initials: G
authors.lastname: Yee
authors.forename: Y
authors.initials: Y
authors.lastname: Huh
authors.forename: E J
authors.initials: EJ
authors.lastname: Freireich
authors.forename: S
authors.initials: S
authors.lastname: Stass
mesh_terms: D000293:Adolescent; D000328:Adult; D001853:Bone Marrow / Q000201:enzymology / Q000473:pathology / Q000648:ultrastructure*; D006801:Humans; D007150:Immunohistochemistry; D015456:Leukemia, Biphenotypic, Acute / Q000097:blood* / Q000201:enzymology / Q000235:genetics; D008297:Male; D008854:Microscopy, Electron; D009195:Peroxidase / Q000378:metabolism*; D010641:Phenotype; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000097:blood* / Q000201:enzymology / Q000235:genetics
chemical_list: D009195:Peroxidase