Structural features of FL 3.

(A) FL 3a. Note that the neoplastic follicular infiltrates are poorly demarcated to the surrounding interfollicular zone and seem to merge with the T-cell area. (B) In contrast, in FL 3b, follicles are sharply demarcated, and there is no merging with the interfollicular infiltrate. Original magnification, × 150. Stained with Giemsa.