[1284] SOX11 Is a Marker of Follicular Dendritic Cell Neoplasms.

Alison R Huppmann, Alina A Leung, Elaine S Jaffe, Mark Raffeld, Stefania Pittaluga. NIH/NCI, Bethesda, MD

Background: Dendritic cell neoplasms (DCNs) are difficult to classify on the basis of morphologic features alone. While immunostains are often helpful to clarify the diagnosis, some cases still cannot be definitively categorized. Clusterin has been identified as a reliable marker to separate follicular dendritic cell tumors (FDCTs) from other DCNs. However, this marker does not always correlate with other diagnostic methods. SOX11 is a transcription factor in the SoxC group of proteins, which also includes SOX4 and SOX12. SOX11 is expressed in mantle cell lymphoma, lymphoblastic malignancies, and Burkitt lymphoma as well as mesenchymal stem cells within the bone marrow. We noted that follicular dendritic cells in normal germinal centers also express this marker. Therefore, we aimed to determine whether SOX11 expression could distinguish FDCTs from other DCNs.
Design: The surgical pathology archives of the NIH/NCI were searched for all DCNs diagnosed between 2000 and July 2010 with material available for immunostaining. All were stained with a rabbit polyclonal SOX11 antibody (Sigma-Aldrich, St. Louis, MO) at a 1:200 dilution. Positive staining was defined as strong nuclear staining in the majority of tumor cells. Tonsillar tissue was used as a positive control. Results of additional stains used at the time of the original diagnosis were also noted.
Results: A total of 20 tumors were available for staining, including 13 cases of FDCTs and 7 other DCNs (3 interdigitating dendritic cell and 4 unclassifiable). Various immunohistochemical panels were used at the time of the original diagnosis, with the most commonly antibodies including clusterin, CD21, CD23, S100, CD68, EGFR, Factor XIIIa, CD1a, and SMA. Ten of 13 (77%) FDCTs were SOX11 positive, as were 2/7 (29%) other DCNs. Clusterin was positive in 12/13 (92%) FDCTs and 1/4 (25%) other FDCNs, with a total of 3 cases with discrepant SOX11/clusterin results (1 FDCT, 2 other DCNs).
Conclusions: SOX11 is expressed in both normal and neoplastic follicular dendritic cells. This antibody is a useful part of the immunostain panel for evaluation of DCNs. Evaluation of its expression in additional types of histiocytic and dendritic cell neoplasms should be performed to further delineate its expression profile in these tumors.
Category: Hematopathology

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 237, Tuesday Morning


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