Distinct BCOR expression in the low-grade spindled cell and round cell components of YWHAE-NUTM2 high-grade endometrial stromal sarcoma. Representative H&E (a, c) and immunohistochemical stains (b, d) demonstrating diffuse nuclear BCOR staining that may be moderate (b) or strong (d) in intensity. The low-grade component (e, top left) shows focal, weak BCOR immunostaining (f, top left) compared to strong and diffuse BCOR expression (f, bottom right) in the round cell component (e, bottom right).