Myeloperoxidase (MPO) and Periodic acid schiff's (PAS) are the two basic cytochemical stains, commonly used in diagnosis and typing of acute leukemias. MPO positive blasts are quite specific for acute myeloid leukemia (AML). However PAS block positivity is seen in Acute "Lymphoblastic" Leukemia (ALL), which has significance in absence of MPO positivity Perioral pallor and Dennie's line are seen in: