Acute Monocytic Leukemia as an Explanation for "Hiatus Leukemicus" and "Myelo-Monocytic Leukemia"

The term "hiatus leukemicus" suggests a jump in cell development from an early stage to a late stage with nothing in between, analogous to changing from the appearance of a 10 year old to that of a 60 year old without any intermediate stages. The term "myelo-monocytic leukemia" suggests leukemia involving 2 distinct cell series. Better methods for identification of promonocytes indicate that both of these pictures are usually due to cases of acute monocytic leukemia misdiagnosed as chronic granulocytic leukemia. Monocytic leukemias have a greater tendency than other myelophthisic processes to chase normal immature cells of the granulocytic and erythrocytic series into the blood stream. The result is that blast and pro cells actually belonging to the monocytic series are frequently misinterpreted as myeloblasts and progranulocytes because of the association with normal progranulocytes and myelocytes. These misdiagnoses result in reports of too low a proportion of acute monocytic leukemias among the total leukemic population, account for a belief that leukemia is due to maturation arrest rather than early cell death or shortening of the n-cell life span, and for naming leukemias for cells more mature than the alpha-cell. Only the alpha-cell can maintain the necessary somatic genetic continuity.