Evaluation of malignant lymphomas using three classifications and the working formulation. 482 cases with median follow-up of 11.9 years

Three classifications and the Working Formulation for non-Hodgkin's lymphomas have been studied in 482 patients with a median follow-up of 11.9 years. Each classification was evaluated independently, and their similar and discrepant aspects were analyzed by comparing subgroups in the different schemes. Clinical staging was essential in the evaluation of some categories. There are several differences between the classifications that are not readily reconcilable. The Rappaport classification's principal groups are heterogeneous. Separation of follicular lymphomas into small and large cleaved cell types (Lukes-Collins) is significant. The addition of a follicular mixed cell type (Rappaport, Working Formulation) detracts from this significance. Centrocytic and lymphoplasmacytic tumors (Kiel) are well-defined categories and important in understanding some deficiencies in the other classifications. The small cleaved cell type, diffuse (Lukes-Collins, Working Formulation) is heterogeneous. Diffuse lymphomas of mixed cell types are poorly defined subgroups. Excluding lymphoblastic types, the presence of plasmacytic differentiation is important in identifying the high-grade lymphomas with the poorest prognosis. These results suggest that adjustments should be made in the classifications and in the Working Formulation.