ABSTRACT
Inspite of the modem and sophisticated tools for the immunophenotyping of acute leukemias, yet there are still simpler methods for initial categorization of leukamias into lymphoblastic and non lymphoblastic. The aim of the present study was to identify mast cell chymase as a marker of acute myeloblastic leukemia since they originate from a common progenitor cell. Bone marrow spiration smears from leukemic patients and control were stained for chymase. The normal control had weak positive reaction, the acute lymphoblastic leukemia had negative reactions while in patients with acute myeloblastic leukemia, the chymase reaction was strikingly positive and positivity correlated well with the basophilic count in the peripheral blood and bone marrow smears. A very strong reaction was seen in patients with myeloid blast crisis and in those who were resistant to induction chemotherapy. Therefore, the chymase identification method is a very cheap and convenient tool for the cytochemical diagnosis of acute myeloblastic leukemia