Classification of the Acute Leukaemias

Abstract

A working numerical notation has been devised for the cytomorphological classification of 238 cases of acute leukaemia in adults (20 years and above) admitted by the referring centres in the United Kingdom to the Medical Research Council’s fourth and fifth therapeutic trials in acute myeloid leukaemia. Patients of 20 years and above diagnosed at the referring centes as suffering from undifferentiated leukaemia were also admitted to the trials. The diagnosis was based on May-Grünwald-Giemsa stained films of bone marrow and peripheral blood. It is intended to correlate statistically the cytomorphological subtypes with the clinical and haematological features recorded at presentation, with the remission frequency and duration, and with the duration of survival.

The notation is flexible and allows for the recognition and easy retrieval of small subgroups not accounted for by conventional nomenclature. The main subtypes are given numbers (MO to M6) and small subgroups are denoted by letters: thus, granulocytic leukaemia showing early but almost exclusively eosinophilic differentiation is designated M2E.