- WHO classification grade 1, 2, or 3a (> 15 centroblasts per high power field with centrocytes present) that is stage III, IV, or bulky (i.e., single mass ≥ 7 cm in any unidimensional measurement) stage II disease NOTE: *Bone marrow biopsies as the sole means of diagnosis are not acceptable, but they may be submitted in conjunction with nodal biopsies; fine-needle aspirates are not acceptable for diagnosis