What type of leukemia is characterized by high WBC and the Philadelphia chromosome?

Chronic myelogenous leukemia (CML) is characterized by the presence of high white blood cell (WBC) counts and the Philadelphia chromosome, which is a specific genetic abnormality resulting from a translocation between chromosomes 9 and 22. This genetic change leads to the formation of the BCR-ABL fusion gene, which plays a crucial role in the pathogenesis of CML.

In CML, the elevated WBC count is primarily due to the overproduction of myeloid cells, which can overwhelm the normal hematological function of the bone marrow. The presence of the Philadelphia chromosome is pivotal in establishing the diagnosis and further informs treatment strategies, particularly with tyrosine kinase inhibitors like imatinib, which specifically target the BCR-ABL fusion protein.

This contrast can be drawn with other forms of leukemia. For instance, acute myeloid leukemia typically does not show the Philadelphia chromosome and is marked by an increase in immature myeloid cells. Chronic lymphocytic leukemia usually presents with high lymphocyte counts rather than elevated WBC due to myeloid lineage. Acute lymphoblastic leukemia, while it can involve high WBC counts, does not usually involve the Philadelphia chromosome as a defining feature in most cases. Thus,