Mantle cell lymphoma (MCL) accounts for 5% to 10% of mature B-cell neoplasms and is an aggressive disease genetically characterized by overexpression of cyclin D1 (CCND1), an important regulator of the G1/S phase of the cell cycle, due to the specific translocation t(11;14)(q13;q32). Cyclin D1 overexpression is the hallmark of MCL. However, approximately 5%-10% of MCLs lack cyclin D1 expression and may be misdiagnosed by overreliance on cyclin D1 IHC. Recently, SOX-11 protein expression in MCL has been investigated by immunohistochemistry. Two studies have evaluated SOX-11 expression in MCL and found strong nuclear expression of SOX-11 in almost all cyclin D1-positive MCL (93%-100%). In all 13 cases of cyclin D1-negative MCL, SOX-11 was strongly expressed. The authors also found that blastoid variant of MCL can be differentiated from CD5+ diffuse large B cell lymphoma, which was negative for SOX-11. In summary, nuclear protein expression of SOX-11 is highly associated with both cyclin

SOX11 [MRQ-58]

Mantle cell lymphoma (MCL) accounts for 5% to 10% of mature B-cell neoplasms and is an aggressive disease genetically characterized by overexpression of cyclin D1 (CCND1), an important regulator of the G1/S phase of the cell cycle, due to the specific translocation t(11;14)(q13;q32). Cyclin D1 overexpression is the hallmark of MCL. However, approximately 5%-10% of MCLs lack cyclin D1 expression and may be misdiagnosed by overreliance on cyclin D1 IHC. Recently, SOX-11 protein expression in MCL has been investigated by immunohistochemistry. Two studies have evaluated SOX-11 expression in MCL and found strong nuclear expression of SOX-11 in almost all cyclin D1-positive MCL (93%-100%). In all 13 cases of cyclin D1-negative MCL, SOX-11 was strongly expressed. The authors also found that blastoid variant of MCL can be differentiated from CD5+ diffuse large B cell lymphoma, which was negative for SOX-11. In summary, nuclear protein expression of SOX-11 is highly associated with both cyclin D1-positive and negative MCL. The detection of this transcription factor is a useful biomarker for identifying true cyclin D1-negative MCL. SOX-11 IHC is of value in further defining pathologic features of CD5+ DLBCL. Routine use of anti-SOX-11 in cases of suspected CD5+ DLBCL might help identify additional cases of cyclin D1-negative blastoid MCL. SOX-11 can also be detected in some BL, LBL and T-PLL, although the different morphological and phenotypic features of these malignancies allow easy recognition of the cases of cyclin D1-negative MCL.

SOX11 [MRQ-58]