Page 189 - Clinical Hematology Atlas

CHAPTER 17 MYELOPROLIFERATIVE NEOPLASMS 173

LAP is an enzyme found in secondary granules of neutrophils. LAP activity is scored from 0 to
41 in the mature segmented neutrophils and bands. One hundred cells are scored and results
are added together for the LAP score. A normal score is approximately 20 to 100. Low (,20)
scores may be found in untreated CML, paroxysmal nocturnal hemoglobinuria, sideroblastic
anemia, and myelodysplastic syndromes. Higher scores may be found in leukemoid reactions
(Table 17-2).

TABLE 17-2 Comparison of Chronic Myelogenous Leukemia and Leukemoid Reaction
in Peripheral Blood
CML Leukemoid Reaction
Neutrophils Increased with immature Increased with immature forms;
cells; peaks at myelocyte and orderly progression of maturation
segmented neutrophil stages stages with no peaks
Eosinophils Increased with immature forms Normal
Basophils

Platelets Abnormal number Normal
Abnormal morphology
Dyspoiesis Present Absent, but may be reactive
changes
Leukocyte alkaline Markedly decreased Increased
phosphatase
CML, Chronic myelogenous leukemia.