Lymphoid crisis with T‐cell phenotypes in a patient with Philadelphia chromosome negative chronic myeloid leukaemia

A case of Philadelphia (Ph1) chromosome negative chronic myeloid leukaemia (CML) developed lymphoid crisis. Immunological marker studies disclosed that the lymphoid cells were sheep erythrocyte-rosetting-, Leu-1+, Leu-5+, OKT-4+, OKT-8+, common ALL antigen-, HLA-DR-, cytoplasmic and surface immunoglobulin-, MAS 036C(antithymocyte)+ (after in vitro culture) and terminal deoxynucleotidyl transferase-, indicating T-cell phenotypes, probably of common thymocytes. Cytochemical staining also demonstrated immature T-cell characters: dot-positivity for acid phosphatase and beta-glucuronidase, and negative for acid alpha-naphthyl acetate esterase. All bone marrow metaphases exhibited normal karyotypes. Our observation suggests that the neoplastic features of a common stem cell for myeloid and lymphoid cell lines are very similar in Ph1 positive and negative CMLs, and that the stem cell can differentiate towards T-lineage.