[1381] Estrogen Receptor Is Frequently Expressed by Follicular Dendritic Cell Sarcomas

Karen L Grogg, Mark Law, Ahmet Dogan. Mayo Clinic, Rochester, MN

Background: Expression of estrogen receptor has been recognized in the follicular dendritic cells associated with reactive lymphoid follicles (Sapino et al. Am J Pathol 2003; 163, 1313-1320). This finding indicates a potential role for the endocrine system in regulation of the immune response through modulation of the dendritic cell population. In this study we investigate the expression of estrogen receptor in a series of follicular dendritic cell sarcomas.
Design: Eighteen cases of follicular dendritic cell sarcoma were assessed by immunohistochemistry IHC) using antibodies to estrogen receptor (rabbit monoclonal SP1, Ventana Medical Systems, Tucson, AZ) and the follicular dendritic cell marker CXCL13 (mouse monoclonal 53610, R&D Systems, Minneapolis, MN). In addition, expression of ER mRNA and CXCL13 mRNA was confirmed by in situ hybridization using a novel and highly sensitive hybridization and amplification system (RNAscope, Advanced Cell Diagnostics, Hayward, CA).
Results: Eight of eighteen cases (44%) showed positive staining for ER by IHC; sixteen of eighteen cases (89%) showed positive staining for CXCL13 by IHC. ER positivity was generally focal, with the strongest staining in areas of nodular growth. ER positivity in FDCS was seen in 33% of male patients and 67% of female patients. Two ER positive cases and four ER negative cases were confirmed to show positivity or negativity, respectively, for ER RNA transcripts by RNA ISH. Four cases were equivocal for ER by RNA ISH. Results for CXCL13 RNA ISH correlated with IHC in all ten cases studied, with a typically more robust signal than IHC.
Conclusions: Expression of ER was observed in 44% of follicular dendritic cell sarcomas. This finding raises the possibility of a role for this molecule in the pathogenesis of this neoplasm, and it may also provide a therapeutic target for cases showing ER expression. The robust staining for CXCL13 by RNA ISH shows promise as a diagnostic tool, as CXCL13 is a difficult target for IHC.
Category: Hematopathology

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 180, Tuesday Morning


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