Which laboratory finding is least consistent with chronic myeloid leukemia (CML)?

Which laboratory finding is least consistent with chronic myeloid leukemia (CML)?

• A. Decreased LAP score
• B. Increased LAP score
• C. Philadelphia chromosome presence
• D. Basophilia

Answer: (B)

LAP score helps differentiate CML from reactive neutrophilia. In CML, neutrophils are part of a malignant clone and show reduced enzyme activity, so the leukocyte alkaline phosphatase score is typically low. The Philadelphia chromosome with BCR-ABL fusion and basophilia are hallmark features of CML, making them consistent findings. An increased LAP score, as seen in leukemoid reactions or reactive neutrophilia, does not fit CML, so it is the least consistent laboratory finding for this disease.

LAP score helps differentiate CML from reactive neutrophilia. In CML, neutrophils are part of a malignant clone and show reduced enzyme activity, so the leukocyte alkaline phosphatase score is typically low. The Philadelphia chromosome with BCR-ABL fusion and basophilia are hallmark features of CML, making them consistent findings. An increased LAP score, as seen in leukemoid reactions or reactive neutrophilia, does not fit CML, so it is the least consistent laboratory finding for this disease.