Acute monocytic leukemia (AMoL, or AML-M5) is a type of acute myeloid leukemia. In AML-M5 >80% of the leukemic cells are of monocytic lineage. This cancer is characterized by a dominance of monocytes in the bone marrow. There is an overproduction of monocytes that the body does not need in the periphery. These overproduced monocytes interfere with normal immune cell production which causes many health complications for the affected individual.

Reference
Wiki: Acute monocytic leukemia