The contribution of cytochemistry and immunophenotyping to the
reproducibility of the FAB classification in acute leukemia
GP Browman, PB Neame and P Soamboonsrup
Intraobserver and interobserver reproducibility of the FAB classification
was assessed for two independent observers whose decisions are acted on for
treatment of patients with acute leukemia in the Hamilton region.
Intraobserver reproducibility was assessed for Wright-stained preparations
that were examined independently on two consecutive occasions at least 2
weeks apart. A third reading was performed with Wright stain and
cytochemical data, and the fourth reading was done with addition of
immunophenotype data. Concordance was calculated using a statistic that
corrects for chance-expected agreement (k), and a weighted statistic that
takes into account the seriousness of disagreements was used. Samples were
available for morphological and cytochemical assessment on 105 patients,
and immunophenotype data were available on 93 specimens. Intraobserver
concordance was 64.8% and 70.5% for observers A and B, respectively, with
kappa values of .56 and .62. There were 37 discordant readings for observer
A and 31 for observer B, with each observer discordant between
lymphocytic:nonlymphocytic phenotypes in ten cases. Concordance between
observers was 63% (k = .54) and 72% (k = .65) for each of two separate
readings for Wright-stained preparations only. Reproducibility improved to
89% (k = .86) when cytochemistry was added. When immunophenotype
information was provided in addition to Wright-stained and cytochemical
preparations, the agreement was 99%. Lymphocytic:nonlymphocytic discordance
between observers occurred on nine occasions when Wright- stained
preparations only were available and four times when cytochemistry was
added; it did not occur with immunophenotyping. The study suggests that
immunophenotyping, when added to morphological assessment of acute
leukemia, may contribute substantially to agreement between observers.
Volume 68,
Issue 4,
pp. 900-905,
10/01/1986
Copyright © 1986 by The American Society of Hematology
