Intraobserver and interobserver reproducibility of the FAB classification in acute leukaemia.

Intraobserver and interobserver reproducibility of FAB classification for acute leukaemia was assessed using the modified criteria of the FAB classification. Leishman stained peripheral smear and May Grunwald Giemsa stained bone marrow smears from 72 cases of acute leukaemia were used for this purpose. Cytochemical stains used were peroxidase, PAS and Sudan black B. Intraobserver and interobserver concordance/discordance was calculated. Kappa statistic was used to correct the chance expected agreement. Intraobserver and interobserver concordance was 76% which improved to 91% when cytochemistry was included. Lymphocytic/Nonlymphocytic concordance was 87.5% and 90% respectively for intraobserver and interobserver groups.