CHRONIC GRANULOCYTIC LEUKAEMIA
This patient was a middle aged man who first presented three years before his death with haematemesis and malaena. On examination he had hepatosplenomegaly. His white cell count was 82,000 per cmm. (82 x 109 per L.) Immature granulocytes were present in the peripheral blood.
The femoral shaft has been sawn longitudinally to display the medullary cavity. The yellow fatty marrow has been replaced by solid pale fawn tissue shown histologically to consist of proliferating myeloid cells. This is a case of chronic granulocytic leukaemia.
Chronic granulocytic (myeloid) leukaemia is one of the four conditions known as myeloproliferative diseases. It is a neoplastic disorder of the multipotent haemopoietic stem cell. It is usually a disease of adults between the ages of 25 and 60. There is an initial protracted phase of the illness in which there is a markedly elevated white cell count (e.g. above 100 x 109 per L.) and marked splenomegaly. All stages of granulocyte differentiation are present in the peripheral blood, including large numbers of mature neutrophils. These cells are however abnormal in that they lack the enzyme alkaline phosphatase. This is the basis of a simple laboratory test for the disease, the N.A.P. (neutrophil alk. phos.) score. In the chronic phase of the illness, the Philadelphia chromosome is present in the bone marrow. This is a reciprocal translocation involving the long arm of chromosome 22 and another chromosome, usually 9. In the chronic phase, the disease may be regarded as being due to a failure of normal regulation of granulocyte proliferation. The disease usually terminates after about 3 years in blastic crisis, i.e. a terminal acute leukaemia which has a very poor prognosis. The onset of the terminal phase is associated with the appearance of additional chromosome abnormalities in the bone marrow.