Mantle cell lymphoma (MCL) is a mature, aggressive B-cell lymphoma with a CCND1 translocation, usually presenting at an advanced clinical stage, and commonly involving the lymph nodes, spleen, bone marrow, and extranodal sites (includes the gastrointestinal tract and Waldeyer ring) [19]. The gene discussed is CCND1; the disease is B-cell non-Hodgkin lymphoma.