Sequential development of mantle cell lymphoma following chronic lymphocytic leukemia

: Richter syndrome (RS) is the development of an aggressive lymphoma in patients with chronic lymphocytic leukemia (CLL). Most cases of diffuse large B-cell lymphoma variant of RS are clonally related to the original CLL. Here, we present a case of mantle cell lymphoma (MCL) that developed sequentially during the clinical course of CLL. A 72-year-old man had been diagnosed with CLL 16 years ago and was followed-up without treatment. He developed autoimmune hemolytic anemia 2 years ago, which resolved with rituximab and prednisolone treatment. Subsequently, he presented with fever, abdominal bloating, and fatigue. Progressive lymphocytosis and splenomegaly with elevated lactic dehydrogenase levels were suggestive of RS. Bone marrow examination revealed a small- to medium-sized lymphoid infiltrate, which was positive for CD5, CD20, CCND1, and SOX-11 and negative for CD23 and LEF1 on immunostaining. Fluorescence in situ hybridization analysis was positive for IgH/CCND1, which indicated MCL. Southern blot analysis showed that both the MCL and the previous CLL expressed different IgH gene rearrangement bands. At the time of relapse or progression of CLL, sequential development of MCL should be considered.