The French-American-British (FAB) Co-operative Group has developed proposals for the classification of the acute leukemias (the FAB classification) which should permit a more uniform system of classification and more accurate recording of the distribution of cases entered into clinical trials.
Since 1978, this classification has been accepted and is still in use in our University Hospital.
From June 9th to August 5th 1980, according to this classification, a panel of four hematologists (A, B, C and D) had examined bone marrow smears from 70 patients with acute leukemia or disorders that might be confused with acute leukemia.
Reproducibility of diagnosis by one of the panelist “A” who has been examining bone marrow smears in our laboratory was satisfactory (90.3% reproducibility). But complete agreement among the observers was poor (39 out of 70 cases, 55.7%, for A, B and C: 8 out of 23 cases, 34.8%, for A, B, C and D)
These observations suggest that the diagnostic criteria of the FAB classification may not be applied uniformly within the panel.
After the first trial, the four panelists had a meeting to reconsider the criteria of the FAB classification, and a discussion on Wright-Giemsa stained films from 24 selected cases was made to make accurate recording of the cases.
After this meeting, from September 16th to November 8th 1980, a similar test was carried out on 46 cases excluding dysmyelotoietic syndrome (DMPS).
Complete agreement become higher in the second test (39 out of 46 cases, 84.8% for A, B and C: 31 out of 46 cases, 67.4% for A, B, C, and D).
We concluded that recent attempts to define the types of acute leukemia by the FAB classification have been welcomed, but it is still difficult to get a high degree of diagnostic agreement for patients with acute leukemia form morphological findings alone. It was also confirmed from this study that a few of the cases of acute leukemia examined in Japan were not considered to be compatible with any types of acute leukemia described in the FAB classification.
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