[735] Double Immunostain with SATB2/Cytokeratin 20 Is Useful in the Differentiation of Appendiceal from Ovarian Mucinous Neoplasms

Rachel M Roth, Jon B Rock, William L Marsh, Xiang Ao, Adrian A Suarez, Wendy L Frankel. Ohio State University Medical Center, Columbus, OH

Background: SATB2 is a DNA-binding protein involved in transcriptional regulation and chromatin remodeling. SATB2, CDX2, cytokeratin 20 (CK20), and Villin are all expressed in most colon cancers. Mucinous carcinomas in the peritoneal/pelvic cavities may be of gynecologic or gastrointestinal origin. We investigated the utility of SATB2 in distinguishing appendiceal mucinous neoplasms (AMN) from ovarian mucinous neoplasms (OMN), using double immunostains (DS).
Design: AMN and OMN (borderline tumors and carcinomas) from 2000 to 2011 were obtained from our archives, and tissue microarrays of 40 AMN and 18 OMN were made. DS were performed pairing nuclear stains CDX-2 and SATB2 with cytoplasmic stains CK20 and Villin, and stains were scored as positive (> 5% cells staining) or negative.

Expression of CDX-2, SATB2, CK20, and Villin in Appendiceal and Ovarian Mucinous Neoplasms
Appendix37 (92.5%)32 (80%)39 (97.5%)37 (92.5%)
Ovary8 (44.4%)3 (16.7%)6 (33.3%)14 (77.8%)

CK20 was the most sensitive stain for AMN. Villin was the most sensitive for OMN, but also stained many AMN. SATB2 was expressed in the fewest cases at both sites, staining 80% of AMN and 16.7% of OMN.

Double Staining of Appendiceal and Ovarian Mucinous Neoplasms
Appendix both positive36 (90%)34 (85%)31 (77.5%)30 (75%)
Appendix either positive40 (100%)40 (100%)40 (100%)40 (100%)
Appendix both negative0 (0%)0 (0%)0 (0%)0 (0%)
Ovary both positive5 (27.8%)8 (44.4%)0 (0%)1 (5.6%)
Ovary either positive9 (50%)14 (77.8%)9 (50%)16 (88.9%)
Ovary both negative9 (50%)4 (22.2%)9 (50%)2 (11.1%)

All AMN expressed at least one of the stains in each DS, and many AMN stained for both. DS with Villin were least useful, as Villin was commonly expressed at both sites. DS for SATB2/CK20 showed the greatest potential clinical utility. When both SATB2 and CK20 were positive, OMN was unlikely (0%) compared to AMN (77.5%). Conversely, when both were negative, OMN (50%) was much more likely than AMN (0%). Results with CDX2 DS were similar to SATB2 DS, but more OMN expressed CDX2, decreasing specificity for appendix. In cases with one positive and one negative stain, the site was not as clear, but favored appendix, especially if SATB2 was the positive stain.
Conclusions: The use of 2, rather than 1 immunostain, improves the distinction of AMN from OMN. The SATB2/CK20 DS is useful in distinguishing AMN from OMN in the peritoneal/pelvic cavity, particularly if material is limited. In challenging cases, the addition of CDX2 may be helpful.
Category: Gastrointestinal

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 109, Monday Morning


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