<prompt> LAP score is maximum in?CMLAMLEssential thrombocytosisPolycythemia vera  <response>: Answwr is option 4 A Leukocyte Alkaline Phosphatase LAP score is still requested from the hematology laboratory as an aid in differential diagnosis in the peripheral hospital setting where molecular biology techniques are not readily available. The LAP score is usually decreased in chronic myelogenous leukemia and paroxysmal nocturnal hemoglobinuria, while it is increased in leukemoid reaction and polycythemia vera. 