Simultaneous evaluation for terminal deoxynucleotidyl transferase and myeloperoxidase in leukemia.

A technique for dual staining of cells using terminal deoxynucleotidyl transferase (TdT) and myeloperoxidase (MPO) is described. The technique has been applied to cells of two patients. One patient had chronic myelomonocytic leukemia evolving into acute myelomonocytic leukemia. The other patient had chronic myelogenous leukemia in blast crisis. Our findings indicate that TdT and MPO are exclusive markers except for a rare precursor cell with dual staining in one patient. This study supports the concept of acute mixed leukemia.