Histological classification of chronic granulocytic leukaemia

Summary. On the basis of the trephine marrow histology at presentation, 52 Ph1 positive cases of chronic myeloid leukaemia were divided into two subgroups, classical chronic granulocytic leukaemia (CGL) and chronic megakaryocytic granulocytic myelosis (CMGM). In 24 cases in which conventional therapy had preceded trephine biopsy, the distribution of cases between the two groups was found to have been significantly altered. Subsequent analysis was therefore confined to the remaining 28 untreated cases; of these 15 were classified as CGL and 13 as CMGM; no statistically significant difference was found between the two groups in respect of patient's age, leucocyte counts, platelet counts, NAP scores or of occurrence of ‘blast’ crisis. The differential diagnosis between idiopathic myelofibrosis (IMF) and CMGM subgroup is discussed. It was concluded that classification of chronic myeloid leukaemia on the basis of marrow histology should be restricted to Ph1 positive cases in order to obviate the possible inclusion of cases of IMF within the CMGM subgroup.