The current study is a multi-faceted examination of yolk sac tumor-like phenotypes in endometrial tumors, based on an analysis of 3 groups of uterine tumors: Group 1: 9 endometrial tumors that had been classified as yolk sac tumor, or as having a yolk sac tumor component, were assessed with a 35-marker immunohistochemical panel, with the goal of defining their immunophenotypic spectrum; Group 2, comprised of 70 endometrial carcinomas of various histotypes, were analyzed for their expression of SALL4, Glypican-3, and AFP, to assess the specificity of these markers for yolk sac tumors relative to endometrial carcinomas; Group 3, comprised of 626 archived cases of endometrial carcinoma/carcinosarcoma, reviewed to define the frequency of yolk sac tumor-like morphology therein.
This 18-year-old woman underwent laparoscopic pelvic tumor resection, considered her first surgery, 2 years ago, and pathology revealed YST with initial alpha-fetoprotein (AFP) level measuring >3,000 ng/mL.
Coexpression of CAM5.2, SALL4, glypican-3, and AFP provides the best support for YST differentiation; however, it has to be noted that none of these markers is specific for these tumors and immunohistochemical results will always have to be interpreted in the context of morphologic, clinical, and radiologic information.
Other markers had higher specificity for each cellular lineage; napsin-A and PAX8 were expressed only in CCC, while SALL4, villin, AFP and HepPar-1 were positive in the glandular YST component but negative in the clear cell component.
The intestinal-type mucinous glands were immunoreactive for SALL4 (4 cases), AFP (4 cases), glypican 3 (1 case), CDX2 (6 cases), and villin (7 cases), markers that are commonly expressed in YSTs, although the latter 2 markers would be expected to be positive in intestinal-type glands.
For germ cell tumors, the mean preoperative serum α-fetoprotein (AFP) level was significantly higher in patients with yolk sac tumor than in those with teratomas (2,078 ng/mL vs 5.7 ng/mL).
This proportion of patients is even lower for those with seminomas or pure embryonal carcinomas as alpha-fetoprotein is predominantly related to yolk sac tumor and human chorionic gonadotropin to choriocarcinoma.
We analyzed EPCAM expression by quantitative RT-PCR in 48 fresh-frozen GCT specimens of different histology (10 mature teratoma, MT; 6 immature teratoma, IT; 7 dysgerminoma; 6 mixed malignant GCTs; 19 yolk sac tumor, YST) and in the GCT cell lines NCCIT, TE76.T, JAR and 2102Ep, and correlated its expression with AFP and hCG protein levels, histologic differentiation, and clinical follow-up data.
The cells were transplanted into the cheek pouch of hamsters and produced an endodermal sinus tumor. alpha-Fetoprotein subfractions in the conditioned media were studied by a modified method of lectin affinity crossed-line immunoelectrophoresis, and we found that the HAEST cells produced concanavalin A nonreactive subfraction, lentil lectin weakly reactive subfraction, phytohemagglutinin-E reactive subfraction and phytohemagglutinin-E nonreactive subfraction, which were predominantly synthesized by the fetal yolk sac, at an early stage of gestation.
In spite of variations of the AFP profile in cancer patients, in most cases it was possible to differentiate primary liver cancer from yolk sac tumour and from liver metastases of cancer.