102. A 69-year-old man is scheduled for surgery, but the procedure is canceled because of abnormal findings in the preoperative blood work. A CBC shows leukocytosis (WBC = 124,000/mL), consisting mainly of maturing neutrophils. Basophilia and eosinophilia are also observed. The platelet count is 820,000/μL. A t(9;22)(q34;q11) translocation is documented. A bone marrow biopsy is shown in the image. Which of the following best characterizes the pathogenesis of the hematologic condition encountered in this patient?
Blocked differentiation of pre-B cells
Blocked differentiation of pre-T cells
Maturational arrest of lymphoid progenitor stem cells
Transformation of a pluripotent bone marrow stem cell
Answer : D Transformation of a pluripotent bone marrow stem cell
The patient exhibits the Philadelphia chromosome and clinicopathologic features of chronic myelogenous leukemia (CML).
The neoplastic cells in CML are derived from an abnormal pluripotent bone marrow stem cell, which results in prominent neutrophilic leukocytosis over the full range of myeloid maturation.
The other choices relate to cells in the lymphoid lineage.