SOX11 and mantle cell lymphoma: Indeed, MCL is now well recognized as a heterogeneous disease with two main clinical and biological presentations belonging to two distinct categories: nodal MCL, which represents the majority of patients (classical MCL, cMCL 80–90%) and leukemic non-nodal MCL (nnMCL, 10–20%), which can be distinguished based on sex-determining region Y-box 11 (SOX11) expression, immunoglobulin heavy chain variable region (IGHV), mutation load, and clinical behavior [5].