[930] CDX-2 Expression in Malignant Germ Cell Tumors of the Testes, Intratubular Germ Cell Neoplasia and Normal Seminiferous Tubules

Michael J Lee, Adam P Vogt, Adeboye O Osunkoya. Emory University School of Medicine, Atlanta

Background: CDX-2 is a caudal-type homeobox gene, encoding a transcription factor that plays an important role in proliferation and differentiation of intestinal epithelial cells. The utility of antibodies to CDX2 in the identification of adenocarcinomas of the gastrointestinal tract, particularly colorectal adenocarcinomas, in both primary and metastatic settings is well established. Patients with testicular tumors may occasionally lack an obvious palpable mass. However, the expression of CDX2 in malignant germ cell tumors of the testes which have metastatic potential has not been previously studied in a large series.
Design: A tissue microarray (TMA) was constructed from 56 malignant germ cell tumors of the testes including; 24 cases of classic seminoma, 8 cases of embryonal carcinoma, 8 cases of yolk sac tumor, 4 cases of malignant teratoma, 2 cases of choriocarcinoma, and 1 case of spermatocytic seminoma. 10 cases of intratubular germ cell neoplasia (IGCN) and 7 cases of benign testicles with normal seminiferous tubules were also included in TMA. Immunohistochemical stains for CDX2 was performed and analyzed. Only nuclear staining was considered positive.
Results: Positive expression of CDX2 was identified in 2/2 cases (100%) of choriocarcinoma, 4/8 cases (50%) of teratoma, 3/8 cases (38%) of embryonal carcinoma, 3/8 cases (38%) of yolk sac tumor and 1/29 cases (3%) of classic seminoma. CDX2 was negative in all cases of IGCN, normal seminiferous tubules and the only case of spermatocytic seminoma.
Conclusions: The role of CDX-2 in the differentiation of intestinal/enteric epithelial cells may contribute to the formation of trophoblastic, glandular, villous or cystic structures in germ cell tumors of the testes. This study suggests that the expression of CDX2 in a variety of malignant germ cell tumors of the testes may be a potential pitfall in metastatic tumors of unknown primary, which are thought to be of gastrointestinal/colorectal origin but are actually from a clinically occult testicular tumor.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 139, Monday Morning


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