A cyclin D1-negative mantle cell lymphoma with an IGL-CCND2 translocation that relapsed with blastoid morphology and aggressive clinical behavior.

Mantle cell lymphoma (MCL) is a B cell neoplasm characterized by cyclin D1 overexpression; its prognosis is poor, especially when it exhibits a blastoid morphology. Cyclin D1-negative MCL is rare, and its pathogenesis and progression remain unclear. Herein, we describe a cyclin D1-negative, cyclin D2-positive MCL with a CCND2 and immunoglobulin lambda light chain (IGL) translocation. The patient was initially diagnosed with cyclin D1-negative MCL and achieved complete remission via combination chemotherapy and autologous stem cell transplantation. After relapsing, he was diagnosed with a blastoid variant of MCL that showed lymphoid cells with dispersed chromatin and more mitotic figures and higher p53 expression compared with the initial MCL. Despite salvage therapies, the disease became refractory, and the patient died 28 months after initiating chemotherapy. This case demonstrates that blastoid morphology in cyclin D1-negative MCL with IGL-CCND2 translocation indicates progression to a more aggressive neoplasm, similar to cyclin D1-positive MCL.