Acute leukaemia. Light micrograph of blood cells from bone marrow in a case of acute leukaemia. These cells include a polynuclear degranulated basophil and myeloblasts, with signs of abnormal maturation. Leukaemia is a cancer where certain blood cells form in excess. There are several acute forms, classified according to the type of cell affected. Basophils are a type of granulocyte white blood cell. Granulocytes develop from precursor cells called myeloblasts. The orange cells are red blood cells.