Morphologic and IHC features of cyclin D1⁻ MCL. Patients ID38 (CCND2 translocation–negative) and ID44 (IGK-CCND2 translocation–positive). (A-A′) Monomorphic small- to medium-sized cells with slightly irregular hyperchromatic nuclei (H&E; 400×). (B-B′) Nuclear positivity for SOX11. (C-C′) The cellular proliferation marker Ki67 shows positivity in 10%-20% of the neoplastic cells (IHC; 200×). (D) Cyclin D1⁻ MCL with mantle zone growth pattern (ID42). Note the expanded mantle zone (H&E; 100×). (E-F) SOX11 is strongly positive (E) and cyclin D1 is not expressed in the neoplastic cells (F; IHC; 100×).