Leukaemia. Light micrograph of a section through bone marrow tissue from a patient with chronic myeloid leukaemia (CML). The bone marrow is seen to contain many large, abnormal granulocyte cells. CML is a cancer of white blood cells. It usually affects elderly people and has a two-stage course. Initially it develops slowly, causing tiredness, fever and weight loss. The course of the disease then accelerates, and it leads to bone tenderness, anaemia and a weakening of the immune system. If the disease is diagnosed while in its first phase, anticancer drugs and bone marrow transplants may effect a cure. Treatment of the acute phase is rarely effective. Magnification unknown.