[1091] CDX2 Is a Useful Marker To Distinguish Ovarian Primary Carcinoid from Gastrointestinal Neuroendocrine Tumors (NET).

Joshua M Lloyd, Haodong Xu, Chengquan Zhao. UPMC, Pittsburgh, PA; University of Rochester, NY

Background: Primary ovarian carcinoids are the second most frequent monodermal teratomas. They occur in a pure form (15%) or combined with other teratomatous components (85%). Primary ovarian carcinoids and metastatic tumors share similar morphologic features. They can be designated as primary with relative ease when they occur in association with other teratomatous components. However, when they occur in a pure form, metastatic disease must be excluded. Gastrointestinal (GI) NET (carcinoid) are more common with the majority arising from small intestine (SI) (29%) and appendix (25%). CDX2 is a nuclear transcription factor critical for intestinal differentiation, and is a relatively specific marker of intestinal epithelium. To the best of our knowledge, CDX2 expression has not been assessed in primary ovarian carcinoids (and is known to be expressed in a subset of GI NET). The aim of this study is to evaluate the expression of CDX2 by immunohistochemistry (IHC) in a large series of primary ovarian carcinoids and primary GI NET.
Design: CDX2 expression was determined by IHC on 28 primary pure ovarian carcinoids, 13 primary ovarian carcinoids arising in association with benign teratomas, 2 ovarian carcinoids metastatic from SI and 70 GI NET (11 stomach, 10 duodenum, 20 SI, 12 appendix, 17 colorectal). Nuclear staining in >5% of cells was considered positive.
Results: None of the 28 primary ovarian carcinoid tumors are positive for CDX2, whereas 49/70 (70%) cases of GI NET and 2/2 (100%) SI NET metastatic to ovary showed strong nuclear staining (diffuse or focal) (Table 1). Two primary carcinoids mixed with benign teratomas showed only weak positivity.

Table 1.
  CDX2+ N/total (%)
Ovarian Carcinoid TumorsPure Primary0/28 (0)
 Primary Mixed with Benign Teratoma2/13 (15)
 Metastatic from Small Intestine2/2 (100)
GI NETStomach0/11 (0)
 Duodenum8/10 (80)*
 Small Intestine19/20 (95)*
 Appendix11/12 (92)*
 Colorectal2/17 (12)
* p<0.0001 as compared to pure primary ovarian carcinoids, Fisher exact test

Conclusions: CDX2 positive carcinoid tumors involving the ovary are unlikely to represent primary ovarian carcinoids and are more likely to be metastatic from the GI tract in the absence of other associated teratomatous elements. CDX2 positivity can be seen in primary ovarian carcinoids that occur in association with benign teratoma suggesting that some of these tumors may arise from GI derived epithelium within the teratoma.
Category: Gynecologic & Obstetrics

Tuesday, March 1, 2011 1:00 PM

Poster Session IV # 131, Tuesday Afternoon


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