Light microscopy of blood smears.

(A) In Romanovsky-stained smears from a normal subject, the PMNs have a granular cytoplasm and a platelet displays granules in the cytoplasm (arrow). (B) In similarly stained smears from a patient with GPS, the PMN cytoplasm appears agranular and platelets are also degranulated (arrow). (C,D) Cytochemical detection of leukocyte alkaline phosphatase. PMN staining intensity is easily detected in the normal state (C) but strongly decreased in GPS compared to normal neutrophils (D).