Blast cells are immature precursors of either lymphocytes (lymphoblasts), or granulocytes (myeloblasts). They do not normally appear in peripheral blood.

There is a progressive accumulation of leukemic cells, because some blast progenitor cells renew themselves and will have a limited differentiated division.

In cytology, a precursor cell, also called a blast cell or simply blast, is a type of partially differentiated, usually unipotent cell that has lost most or all of the stem ...