In which of the following condition PAS test has block positivity: (A) ALL L1, (B) AML, (C) CML, (D) Hodgkins lymphoma
Answer is A. Periodic acid - schiff (PAS) stain is useful for the diagnosis of ALLs and erythroid and megakoryocytic (M6 and M7) type of acute myeloid leukemia.
Block positivity in lymphoblast is oberved in ALL L1 cores.