[1148] CDX2 Expression in Gynecologic Yolk Sac Tumors

MY Ngae, MT Deavers. The University of Texas MD Anderson Cancer Center, Houston, TX

Background: Yolk sac tumor (YST) has a variety of microsopic patterns that can mimic carcinomas. In the gynecologic tract, the glandular variant of YST can be confused with endometrioid adenocarcinoma; papillary, glandular, solid or hepatoid features may be difficult to distinguish from clear cell carcinoma. As such, alpha-fetoprotein (AFP) has traditionally been used to help identify YST. However, AFP can be focal or negative in YSTs and lacks adequate sensitivity and specificity to be used in isolation, with documented expression in other gynecologic and non-gynecologic malignancies. Immunohistochemical reactivity for CDX2 is often used to demonstrate intestinal differentiation in adenocarcinomas. Recently, CDX2 expression has also been found in YSTs of the testis and even lung, but to our knowledge has not been reported in YSTs of the gynecologic tract.
Design: In this study, we evaluate 13 cases of YST collected over an 18 year period for CDX2 expression. Immunohistochemical staining for CDX2 (CDX2-88, 1:50, Biogenics) was performed on BondMax automated immunostainers (ER2 20 minutes). The IHC slides were reviewed in conjunction with the H&E-stained sections. Nuclear staining was graded as follows: 1+ (1-25%), 2+ (26-50%), 3+ (51-75%), 4+ (76-100%). Controls reacted appropriately. The majority of the tumors were located in the ovary, with the exception of 1 endometrial primary, and 1 metastasis to a retroperitoneal lymph node. Of the ovarian tumors, 6 cases were pure YST, 3 cases were mixed YST and teratoma, 1 was a case of YST with endometrioid adenocarcinoma, and the last was a YST with clear cell carcinoma. The endometrial tumor was composed of YST with serous and endometrioid adenocarcinoma. The metastatic YST in the lymph node was associated with an ovarian dysgerminoma.
Results: All the YSTs (and different patterns) had at least 1+ staining for CDX2. There was 2+ staining in the YST associated with clear cell carcinoma of the ovary, and 2-3+ staining in an ovarian mixed germ cell tumor with teratoma and YST components. The different patterns of tumor that demonstrated staining included reticular, polyvesicular-vitelline, solid and papillary forms. Focal staining of the teratomatous intestinal glandular components of the mixed germ cell tumors was noted.
Conclusions: CDX2 can be used as an adjunct to AFP in support of the diagnosis of gynecologic YST. Caution should be exercised in interpreting any positivity for CDX2 in the setting of a teratoma containing components with intestinal differentiation.
Category: Gynecologic & Obstetrics

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 172, Wednesday Afternoon

 

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