Which statement best describes WBC counts typically seen in the condition with a BCR-ABL fusion?

• A. Counts typically around 10,000
• B. Counts typically >50,000
• C. Counts typically >100,000
• D. Counts typically normal

Answer: (D)

BCR-ABL fusion marks chronic myeloid leukemia, a myeloproliferative disorder where constitutive tyrosine kinase activity drives uncontrolled expansion of the myeloid lineage. This leads to marked leukocytosis, so white blood cell counts are typically well above normal—commonly exceeding 50,000 per microliter and often reaching 100,000 or more. The picture is a high white count with a left-shift and immature forms, sometimes with basophilia, rather than a normal or mildly elevated count. So a description of WBC counts typically being greater than 50,000 best fits the condition.