The World Health Organization classification recommends categorizing grade 3 follicular lymphomas based on the presence of centrocytes (grade 3A) or of sheets of centroblasts (grade 3B). The clinical significance of this practice is not known.
To determine whether grade 3 follicular lymphoma subtype is associated with prognosis.
Multi-institutional retrospective case series.
Overall survival.
Forty-five cases of grade 3 follicular lymphoma without diffuse large B-cell lymphoma were studied (35 cases of grade 3A, 10 cases of grade 3B) from 21 men and 24 women (median age, 67 years; mean age, 63.8 years; range, 26-86 years). Follow-up information from the time of diagnosis was available in all patients, with a median follow-up time of 24 months (mean, 34 months; range, 2- 115 months). Treatment information was available in 40 patients. There was no difference in age (P =.45, Wilcoxon test) or stage (P =.76, Fisher exact test) between patients with follicular lymphoma of grade 3A or grade 3B. Furthermore, the Cochran-Armitage test for trends showed no evidence that the proportion of patients with follicular lymphoma grade 3A or 3B increased or decreased with increasing stage at presentation. Kaplan-Meier analysis showed a median overall survival of 44 months from the time grade 3 follicular lymphoma was diagnosed, with no significant difference between cases diagnosed as grade 3A or grade 3B (P =.14, log-rank test). Univariable Cox proportional hazards modeling showed no evidence that an anthracycline-containing chemotherapy regimen or history of lower grade follicular lymphoma affected overall survival.
In this retrospective series, subclassification of grade 3 follicular lymphoma into type 3A and 3B categories had limited clinical and prognostic significance. However, the study was limited by lack of statistical power. Since morphology often provides clues for progress in defining biologic differences, subtyping may still be useful, particularly in the setting of prospective clinical studies.