SOX11 and mantle cell lymphoma: MCL is an heterogeneous disease “per se” and World Health Organization recognizes 2 molecular subtypes that differ in their clinical and biological features: the most common and aggressive conventional MCL (cMCL, SOX11+ and unmutated immunoglobulin heavy chain (IGHV), naïve-like B-cell) and the indolent leukemic non-nodal MCL (nnMCL; SOX11− and mutated IGHV, memory-like B-cell) [1–3].