title: 'Pseudo-lymphoid' leukaemia with unusual features: ultrastructural, immunological, cytogenetic and molecular studies.
abstract: An unusual case of 'pseudo-lymphoid' leukaemia is described. The leukaemic cells resembled small, mature lymphocytes but lacked B- and T-cell membrane markers as well as immunoglobulin (Ig) and T-cell receptor gene rearrangements. They showed, instead, features of early myeloid cells since they expressed 2 myeloid antigens, CDW13 and My9, and displayed peroxidase activity demonstrable by electron microscopy (EM) on unfixed cells. Cytogenetic studies showed monosomy 5, t(4;17) (p12;p11), t(2;3)(p23;q14) and an abnormal chromosome 12. Abnormalities of chromosomes 4 and 5 have been previously associated with 'pseudo-lymphoid' leukaemias. This case illustrates the value of sensitive methods for the characterization of blast cells and for the precise diagnosis of leukaemias with apparent 'lymphoid' morphology.
mesh_terms: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis; D002869:Chromosome Aberrations / Q000235:genetics; D025063:Chromosome Disorders; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007621:Karyotyping; D007945:Leukemia, Lymphoid / Q000235:genetics / Q000276:immunology / Q000473:pathology*; D008854:Microscopy, Electron; D008875:Middle Aged; D009195:Peroxidase; D010544:Peroxidases / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D007527:Isoenzymes; D010544:Peroxidases; D009195:Peroxidase