Periodic acid schiff stain shows block positivity in the following cells:
In acute lymphocytic leukemia (ALL), cells show a varied staining pattern with periodic acid schiff (PAS) stain. Lymphoblasts of ALL may show a coarse block pattern of activity, a finely diffuse pattern, or a combinations of the two patterns, or they may be negative. Cells from Burkitt's lymphoma are generally negative. Ref: Hematology: clinical principles and applications, 2007, Page 401.
Myeloblasts
Lymphoblasts
Monoblasts
Megakaryoblasts