CD10 expression in the 3 histologic patterns of AITL.

Panels A and B show case 2 with histologic pattern I, panels C and D show case 10 with histologic pattern II, and panels E and F show case 28 with histologic pattern III. Numerous medium-sized lymphoid cells in and around the follicles in pattern I (A,B) and II (C,D) are CD10⁺. Panel B shows that the intensity of staining is much higher in these cells compared with weakly staining follicle center B cells. The follicular distribution is lost in pattern III (E) in which a diffuse infiltrate of CD10⁺ cells is seen. Panel F shows that some of these are large atypical lymphoid cells. Original magnification A, C, E, × 40; B, F, × 400; D, × 200.