T(12;14)(p13;q32) is a rare recurrent chromosomal translocation, which has only been identified in a small subgroup of mantle cell lymphoma (MCL) without typical t(11;14)(q13;q32). This rearrangement causes aberrant over-expression of cyclin D2 (CCND2), which disrupts the normal cell cycle. Here we report a subtle case of MCL with t(12;14)(p13;q32) that was initially misdiagnosed as ultra-high risk chronic lymphocytic leukemia (CLL). A 60-year-old male patient presented with obvious leukocytosis and progressive weakness. Morphology of peripheral blood and immunophenotyping by flow cytometry pointed to a diagnosis of chronic lymphocytic leukemia. Fluorescence in situ hybridization (FISH) using IGH-CCND1 probe was negative for CCND1 abnormality, but demonstrated IGH breakapart signals. The initial diagnosis of CLL was established and the patient was treated with six courses of immunochemotherpy with fludarabine, cyclophosphamide and rituximab (FCR). Complete remission (CR) was achieved at the end of treatment, but disease relapsed quickly. The patient was transferred to our hospital, flow cytometry using additional markers showed that the clonal cells were CD200+(dim), CD148+(strong), and chromosome analysis revealed a complex karyotype, 47, XY, t(12;14)(p13;q32), +12, del(9p21), which indicated over-expression of CCND2, and immunostaining showed strong positivity of SOX11 further confirming the characteristics of CCND1-negtive MCL. The final diagnosis was revised to rare subtype of MCL with CCND2 translocation and intensive regimens were employed. This confusable MCL case illustrates the importance of cytogenetic analysis and clinicopathologic diagnosis of this rare category of MCL.
Keywords: CD148; SOX11; cyclin D2; mantle cell lymphoma; t(12;14).