Reproducibility in morphologic classification of non-Hodgkin's lymphomas using the Lukes-Collins system. The Southeastern Cancer Study Group experience.

Five pathologists of the Southeastern Cancer Study Group reviewed routinely prepared histologic sections from 249 cases of non-Hodgkin's lymphoma. They classified these cases morphologically, using criteria of the Lukes-Collins classification system. To evaluate reproducibility in classification, the individual interpretations of each pathologist were compared with a consensus interpretation. The pathologists recognized general morphologic features of follicular center cell lymphomas in 87-94% of such cases, but they identified specific morphologic types much less consistently. Significant differences of interpretation were encountered with respect to small cleaved follicular center cell, large cleaved follicular center cell, and large transformed (large noncleaved) follicular center cell types. Inadequacies of routine histologic sections contributed substantially to these disagreements. Ancillary immunologic technics may be required to improve consistency in recognition of some morphologic types, as well as to characterize cases that are not classified easily by morphology alone.