Embryonic Stem Cell Transcription Factors and D2-40 (Podoplanin) as Diagnostic Immunohistochemical Markers in Ovarian Germ Cell Tumors:

Assessment of Molecular Markers in Pediatric Ovarian Tumors: Romanian Single-Center Experience

Pediatric ovarian tumors exhibit unique diagnostic and therapeutic challenges. This study evaluates the expression of SALL4 and OCT3/4 biomarkers in pediatric ovarian tumors and their associations with tumor subtype, stage, and clinical outcome. A retrospective analysis was conducted on 64 patients under 18 years old, examining demographic data, tumor characteristics, immunohistochemical staining, and clinical outcomes. Our results show that SALL4 was significantly expressed in adenocarcinoma, dysgerminoma (DSG), mixed germ cell tumors (GCTs), and immature teratoma, while OCT3/4 was highly expressed in DSG and mixed GCTs. Both markers are associated with a higher tumor grade and stage, indicating a more aggressive disease. The SALL4 positivity expression was correlated with high alpha fetoprotein (AFP) and lactate dehydrogenase (LDH) levels, while OCT3/4 positivity significantly predicted the risk of subsequent metastasis. The mean progression-free survival (PFS) was notably shorter in patients with positive markers. These findings underscore the diagnostic and prognostic value of SALL4 and OCT3/4 in pediatric ovarian tumors, aligning with previous research and supporting their use in clinical practice for better disease management and patient outcomes.

Cancer Stem Cell Markers Are Differentially Expressed in Malignant Ovarian Germ Cell Tumors

The objective of this study was to analyze the expression and potential clinical role of cancer stem cell (CSC) markers in malignant ovarian germ cell tumors (MOGCT). CD34, CD44, and SOX2 protein expression by immunohistochemistry was analyzed in 49 MOGCT from patients treated in Norway during the period 1980-2011. Expression was analyzed for association with tumor type and clinicopathologic parameters. Tumors were diagnosed as dysgerminoma (DG; n=15), immature teratoma (IT; n=15), yolk sac tumor (YST; n=12), embryonal carcinoma (n=2), and mixed MOGCT (n=5). Tumor cell CD34 expression was significantly more common in YST, whereas stromal expression was only seen in IT (both P <0.001). CD44 was infrequently expressed, most often focally, in tumor cells, particularly in YST ( P =0.026). CD44 was widely expressed in leukocytes, most prominently in DG. SOX2 was most frequently expressed in IT, with predominantly focal expression in some YST and uniform absence in DG ( P <0.001). Stromal CD34 ( P =0.012) and tumor cell SOX2 expression ( P =0.004) were negatively associated with the involvement of the ovarian surface, presumably due to the low incidence of this event in IT. No significant association was found between CSC marker expression and other clinicopathologic parameters, including age, laterality, tumor diameter, and FIGO stage. In conclusion, CSC markers are differentially expressed in various MOGCT types, suggesting differences in the regulation of cancer-related processes. Expression of CD34, CD44, and SOX2 does not appear to be associated with clinical parameters in this patient group.

Immune-related mechanisms and immunotherapy in extragonadal germ cell tumors

Purpose of review

Extragonadal germ cell tumors (EGCTs) are relatively rare tumors, accounting for 1%-5% of all GCTs. In this review, we summarize the current research progress regarding the pathogenesis, diagnosis, and treatment of EGCTs from an immunology perspective.

Recent findings

The histological origin of EGCTs is related to a gonadal origin, but they are located outside the gonad. They show great variation in morphology and can occur in the cranium, mediastinum, sacrococcygeal bone, and other areas. The pathogenesis of EGCTs is poorly understood, and their differential diagnosis is extensive and challenging. EGCT behavior varies greatly according to patient age, histological subtype, and clinical stage.

Summary

This review provides ideas for the future application of immunology in the fight against such diseases, which is a hot topic currently.

Roles of Podoplanin in Malignant Progression of Tumor

Podoplanin (PDPN) is a cell-surface mucin-like glycoprotein that plays a critical role in tumor development and normal development of the lung, kidney, and lymphatic vascular systems. PDPN is overexpressed in several tumors and is involved in their malignancy. PDPN induces platelet aggregation through binding to platelet receptor C-type lectin-like receptor 2. Furthermore, PDPN modulates signal transductions that regulate cell proliferation, differentiation, migration, invasion, epithelial-to-mesenchymal transition, and stemness, all of which are crucial for the malignant progression of tumor. In the tumor microenvironment (TME), PDPN expression is upregulated in the tumor stroma, including cancer-associated fibroblasts (CAFs) and immune cells. CAFs play significant roles in the extracellular matrix remodeling and the development of immunosuppressive TME. Additionally, PDPN functions as a co-inhibitory molecule on T cells, indicating its involvement with immune evasion. In this review, we describe the mechanistic basis and diverse roles of PDPN in the malignant progression of tumors and discuss the possibility of the clinical application of PDPN-targeted cancer therapy, including cancer-specific monoclonal antibodies, and chimeric antigen receptor T technologies.

Malignant Mixed Germ Cell Tumors of the Ovary: An Analysis of 100 Cases Emphasizing the Frequency and Interrelationships of Their Tumor Types

One hundred malignant mixed germ cell tumors of the ovary that occurred in patients 3 to 55 years (mean: 20 y) of age are described. The clinical presentation was usually that of any highly malignant tumor of the ovary (abdominal pain and distension), but rarely (3 cases) endocrine manifestations were present. The tumors were usually unilateral (96%), ranged from 4 to 38 cm (mean: 16 cm), and were uniformly solid or, more often, solid and cystic; occasionally the typical appearance of dysgerminoma could be appreciated. The most common tumor type was yolk sac tumor (91%), followed by dysgerminoma (61%), immature teratoma (58%), embryonal carcinoma (38%), and choriocarcinoma (11%). A variety of admixtures were encountered; dysgerminoma and yolk sac tumor was the most common combination (25% of the tumors) with the 2 components often being sharply demarcated. Immature teratoma and yolk sac tumor was the next most common pairing (20%) followed by yolk sac tumor and embryonal carcinoma, with or without immature teratoma (16%). Tumors with a choriocarcinoma component had the most varied combinations of tumor types. Embryoid bodies were seen in 21% of the tumors, most often as fragmented forms arranged in a nodular manner with yolk sac tumor and/or embryonal carcinoma; uncommonly they occurred singly or in clusters. Numerous confluent well-formed embryoid bodies (polyembryoma) were prominent in 2 tumors. Three tumors had a focal diffuse embryoma pattern. The specific tumor types showed the known diverse spectrum of microscopic appearances, but the frequent haphazard arrangement of 2 or more subtypes often resulted in complex morphology. Overgrowth of another neoplastic component, most often primitive neuroectodermal tumor, occurred in 10% of the tumors further complicating the histologic picture. This is the largest series of ovarian malignant mixed germ cell tumors reported and details their characteristics including associations of their subtypes and the frequent apparent role of embryoid bodies in giving rise to yolk sac tumor and embryonal carcinoma components.

Dysgerminoma of the Ovary: An Analysis of 140 Cases Emphasizing Unusual Microscopic Findings and Resultant Diagnostic Problems

One-hundred fourty pure dysgerminomas were evaluated with particular focus on the microscopic features as seen in 125 cases with available slides. The patients ranged from 8 to 59 years of age (mean, 24.1 y). The tumors, bilateral in 4% of the cases and with a mean tumor diameter of 13 cm, were typically soft, lobulated, homogeneous, and creamy white to tan to yellow but necrosis was found in 13%, hemorrhage in 20%, and focal cystic change in 15%. On microscopic examination, the patterns and other notable features encountered, including their frequency, were as follows: an alveolar pattern resulting from delicate fibrovascular septa (51%), diffuse (33%), macronodular (14%), insular (26%), cords (28%), solid tubular (17%), microspaces (sometimes simulating glands) (12%), follicle-like spaces (5%), prominent fibrous bands (65%), stromal edema (56%), stromal luteinization (9%), granulomatous infiltrate (46%), lymphocytic infiltrate (100%), Langhans cell type giant cells (35%), syncytiotrophoblast giant cells (6%), prominent population of cells with pale to clear cytoplasm (73%), cells with amphophilic to eosinophilic cytoplasm (53%) and vacuolated occasionally signet ring-like cells (7%). Various constellations of the above findings often resulted in an appearance different from that usually portrayed in the literature and certain tumors of very different nature being in the differential such as undifferentiated carcinoma not otherwise specified, small cell carcinoma of hypercalcemic type, and malignant lymphoma. The correct diagnosis can be arrived at by considering the usual relative youth of the patient, often rather characteristic gross features, and most crucially careful attention to the microscopic features and awareness of variant morphologic findings. Those that are particularly problematic based on this study are diffuse growth with inconspicuous fibrovascular septa, macronodules, cords, solid tubular formations, spaces ranging from small to large, and mimicking glands or follicles, prominent fibrous to edematous stroma, and cells with amphophilic to eosinophilic cytoplasm. According to the degree of difficulty and confidence of the interpreter, well-known immunohistochemical features of dysgerminoma, which largely differ from those of other neoplasms in the differential, will aid if felt indicated.

Female Germ Cell Development, Functioning and Associated Adversities under Unfavorable Circumstances

In the present era, infertility is one of the major issues which restricts many couples to have their own children. Infertility is the inability to achieve a clinical pregnancy after regular unprotected sexual intercourse for the period of one year or more. Various factors including defective male or female germ cell development, unhealthy and improper lifestyles, diseases like cancer and associated chemo-or-radiation therapies, congenital disorders, etc., may be responsible for infertility. Therefore, it is highly important to understand the basic concepts of germ cell development including primordial germ cell (PGC) formation, specification, migration, entry to genital ridges and their molecular mechanisms, activated pathways, paracrine and autocrine signaling, along with possible alteration which can hamper germ cell development and can cause adversities like cancer progression and infertility. Knowing all these aspects in a proper way can be very much helpful in improving our understanding about gametogenesis and finding possible ways to cure related disorders. Here in this review, various aspects of gametogenesis especially female gametes and relevant factors causing functional impairment have been thoroughly discussed.

A Comprehensive Review of Biomarker Use in the Gynecologic Tract Including Differential Diagnoses and Diagnostic Pitfalls

Morphologic (ie, hematoxylin and eosin) evaluation of the Mullerian tract remains the gold standard for diagnostic evaluation; nevertheless, ancillary/biomarker studies are increasingly utilized in daily practice to assist in the subclassification of gynecologic lesions and tumors. The most frequently utilized "biomarker" technique is immunohistochemistry; however, in situ hybridization (chromogenic and fluorescence), chromosomal evaluation, and molecular analysis can also be utilized to aid in diagnosis. This review focuses on the use of immunohistochemistry in the Mullerian tract, and discusses common antibody panels, sensitivity and specificity of specific antibodies, and points out potential diagnostic pitfalls when using such antibodies.

Gynecologic Serous Carcinoma: An Immunohistochemical Analysis of Malignant Body Fluid Specimens

CONTEXT.—

Evaluation of fluid specimens involved by serous carcinoma might potentially include PAX8, GATA3, Uroplakin II, SOX2, and SALL4 antibodies. Those markers are commonly employed for diagnosing carcinomas of various types, including urothelial malignancies and germ cell tumors. There have been no comprehensive immunohistochemical studies, to our knowledge, for those markers on fluid specimens involved by serous carcinoma.

OBJECTIVE.—

To evaluate immunohistochemical markers PAX8, GATA3, SOX2, uroplakin II, and SALL4 in the diagnosis of high-grade serous carcinoma in fluid specimens.

DESIGN.—

We examined 113 fluids (96 ascites specimens and 17 pleural fluid specimens) that were positive for carcinoma. Most (94 cases; 83.2%) consisted of high-grade serous carcinoma of Müllerian origin. Nineteen cases of non-high-grade serous carcinoma (including one case of low-grade serous carcinoma) of gynecologic origin were also included as anecdotal data.

RESULTS.—

In 113 fluid specimens with positive results for carcinoma, including nonserous types, 99 (87.6%) had positive results for PAX8, 19 (16.8%) for GATA3; 19 (16.8%) for SOX2, 23 (20.4%) for uroplakin II, and 8 (7.1%) for SALL4. Of 94 fluids (83.2%) involved with high-grade serous carcinoma, 84 (89.4%) had positive results for PAX8, 18 (19.1%) for GATA3, 17 (18.1%) for SOX2, 22 (23.4%) for uroplakin II, and 8 (8.5%) for SALL4. Some of these specimens showed reactivity for more than one immunohistochemical marker.

CONCLUSIONS.—

Most fluids involving high-grade serous carcinoma showed positive results for PAX8, and some cases expressed GATA3, SOX2, uroplakin II, and SALL4. Serous carcinoma in fluids may be positive for immunohistochemical markers not thought of traditionally as associated with gynecologic malignancy, an important consideration in avoiding misdiagnosis.

Diagnostic immunohistochemistry in gynaecological neoplasia: a brief survey of the most common scenarios

Immunohistochemistry is a valuable adjunct in routine gynaecological pathology. The molecular revolution has redesigned knowledge of gynaecological cancers and refined histological classification. The direct consequence has been the progressive introduction of new immunostainings for diagnostic and classification purposes. Hence, we review the routine diagnostic use of immunohistochemistry in the field of gynaecological neoplasia. We reviewed the immunomarkers useful in gynaecological pathology according to literature revision, our personal experience and research findings. We discuss the application of immunohistochemistry to reach the most accurate diagnosis in morphologically equivocal cases of gynaecological pathology and present the appropriate panel of immunomarkers in the most common scenarios of gynaecological pathology. This short review provides an updated overview of the essential immunohistochemical markers currently used in the diagnostics of gynaecological malignancies along with their molecular rationale.

The Utility of Immunohistochemistry in the Differential Diagnosis of Gynecologic Disorders

Context

Immunohistochemistry has assumed an increasing role in the identification and characterization of gynecologic disorders including lesions with deceptively bland morphology, uncommon and underdiagnosed neoplasms, and neoplasms with specific genetic alterations associated with overexpression or loss of expression of specific proteins. The diagnostic accuracy has been significantly improved owing to the discovery and increasing experience with the tumor-associated biomarkers, and the increasing demand for precise tumor classification to assess suitability for the expanding therapeutic modalities including clinical trials.

Objective

To differentiate lesions of the gynecologic tract through the use of effective immunohistochemical panels.

Data Sources

Literature review and authors' personal practice experience.

Conclusions

The application of diagnostic and prognostic immunohistochemical panels has enabled pathologists to better guide therapeutic decisions and to better predict the clinical outcome. It is now well established that the use of ancillary testing, including immunohistochemistry, has a significant power in the identification, differentiation, and classification of reactive, premalignant, and malignant gynecologic disorders. This article discusses the utilities and pitfalls of the commonly used immunohistochemical markers in the context of overlapping morphologic features encountered in the uterus, ovaries, and fallopian tubes.

Germ cell tumors of the ovary: an update

CONTEXT

The field of ovarian germ cell tumors (OGCTs) has remained relatively unchanged in the last 2 decades. However, the introduction of new stem cell pluripotency markers has provided a new understanding into the identification and taxonomy of OGCT types. New data have provided new insights into unusual teratoma-associated autoimmune disorders and the origin of gliomatosis peritonei.

OBJECTIVE

To review the impact of new pluripotency markers in the diagnosis of malignant OGCT (MOGCT) and analyze new nomenclature proposals and clinicopathologic entities.

DATA SOURCES

Ovarian germ cell tumors from routine material and expert consultation files at San Cecilio University Hospital, Granada, Spain, and the relevant literature were reviewed.

CONCLUSIONS

Although a correct diagnosis of MOGCT can often be made with histologic and classic immunohistochemical studies, the new immunohistochemical pluripotency markers give higher diagnostic accuracy. Germ cell tumors represent a caricature of the phases of normal embryonic differentiation from primordial germ and stem cells to extraembryonal and somatic tissue differentiation. Since every stage of differentiation and its related tumor type exhibit characteristic markers, the analysis of their expression facilitates tumor typing, thus complementing the use of classic antibodies. They also allow a more precise evaluation of the degree of immaturity in teratoma. The new term, primitive endodermal tumors, simplifies the understanding of the complex histology of the yolk sac tumor group, as this terminology encompasses its multiple endodermal differentiations. Recently described autoimmune encephalitis due to antibodies against the N-methyl-d-aspartate receptor has become the most frequent autoimmune disorder associated with ovarian teratoma.

Molecular characteristics of malignant ovarian germ cell tumors and comparison with testicular counterparts: implications for pathogenesis

This review focuses on the molecular characteristics and development of rare malignant ovarian germ cell tumors (mOGCTs). We provide an overview of the genomic aberrations assessed by ploidy, cytogenetic banding, and comparative genomic hybridization. We summarize and discuss the transcriptome profiles of mRNA and microRNA (miRNA), and biomarkers (DNA methylation, gene mutation, individual protein expression) for each mOGCT histological subtype. Parallels between the origin of mOGCT and their male counterpart testicular GCT (TGCT) are discussed from the perspective of germ cell development, endocrinological influences, and pathogenesis, as is the GCT origin in patients with disorders of sex development. Integrated molecular profiles of the 3 main histological subtypes, dysgerminoma (DG), yolk sac tumor (YST), and immature teratoma (IT), are presented. DGs show genomic aberrations comparable to TGCT. In contrast, the genome profiles of YST and IT are different both from each other and from DG/TGCT. Differences between DG and YST are underlined by their miRNA/mRNA expression patterns, suggesting preferential involvement of the WNT/β-catenin and TGF-β/bone morphogenetic protein signaling pathways among YSTs. Characteristic protein expression patterns are observed in DG, YST and IT. We propose that mOGCT develop through different developmental pathways, including one that is likely shared with TGCT and involves insufficient sexual differentiation of the germ cell niche. The molecular features of the mOGCTs underline their similarity to pluripotent precursor cells (primordial germ cells, PGCs) and other stem cells. This similarity combined with the process of ovary development, explain why mOGCTs present so early in life, and with greater histological complexity, than most somatic solid tumors.

Prognostic impact of the cancer stem cell-related marker NANOG in ovarian serous carcinoma

OBJECTIVE

The objective of this study was to evaluate the prognostic significance of NANOG expression in ovarian serous carcinoma.

METHODS

The expression of NANOG was evaluated in 6 ovarian carcinoma cell lines, paclitaxel-resistant SKOV3 cells, and SKOV3 spheroid cells with semiquantitative reverse transcription-polymerase chain reaction and Western blotting. NANOG expression was also measured immunohistochemically in a tissue microarray containing ovarian tissues from 74 patients with ovarian serous carcinoma and 24 with ovarian serous cystadenoma. Each sample was scored based on signal intensity and proportion, and a score greater than 4 was considered "positive."

RESULTS

NANOG mRNA expression was variable in different ovarian cancer cell lines. The mRNA level of NANOG was increased in the paclitaxel-resistant SKOV3 cells and SKOV3 spheroid cells compared with that in the SKOV3 cells. NANOG expression was positive in 21.6% of 74 ovarian serous carcinoma tissues, but none of the ovarian serous cystadenoma tissues were positive. Positive NANOG expression was associated with residual tumor size after surgery (P = 0.032). The overall survival of the patients with positive NANOG expression was poorer than that of the patients with negative NANOG expression (P = 0.020). In patients with stage I and II disease, positive NANOG expression was independently associated with shorter overall survival compared with negative NANOG expression (40 vs 120 months, respectively; P = 0.031).

CONCLUSIONS

Positive NANOG expression is associated with poor prognosis of ovarian serous carcinoma. NANOG has potential as a predictor of survival for patients with ovarian carcinomas and may be involved in the mechanism of chemoresistance.

Nanog is highly expressed in ovarian serous cystadenocarcinoma and correlated with clinical stage and pathological grade

OBJECTIVE

Nanog is overexpressed in embryonic stem cells for cell self-renewal and differentiation. We investigated whether the Nanog expression is associated with the occurrence and development of ovarian cancer.

METHODS

Immunohistochemistry was used to examine the expression of Nanog in 43 normal ovarian epithelia, 110 serous cystadenomas, 80 borderline serous cystadenomas, and 107 serous cystadenocarcinomas. In the meantime, their association with various clinicopathologic features was assessed.

RESULTS

The expression intensity of Nanog in normal ovarian tissue, benign, borderline, and malignant tumors showed a gradual rising trend. Among the serous cystadenocarcinomas, 42.86% were detected to be positive for stage I, 70.97% for stage II, 95.31% for stage III, and 100% for stage IV. There was a strong correlation between Nanog and clinical stage (r = 0.418, p = 0.000). Besides, there was a 55.56% positive expression of grade I, 73.68% of grade II, and 96.67% of grade III. The correlation between Nanog and differentiation grade was dramatic (r = 0.692, p = 0.000).

CONCLUSIONS

Nanog was highly expressed in ovarian serous cystadenocarcinoma, and showed a positive correlation with clinical stage and grade. Nanog may play an important role in the development of dedifferentiation and progression of serous ovarian carcinoma.

Transcription factors and ovarian functions

This study represents a first review of contemporarily knowledge concerning involvement of transcription factors in control of different ovarian functions. After introduction of basic functions and classification of transcription factors, the available data concerning involvement of transcription factors in control of the following ovarian events are present: follicular development and selection, ovarian cell proliferation and cancerogenesis, ovarian cell apoptosis, ovarian secretory activity, oocyte/cumulus maturation, ovulation and luteogenesis, mediation effect of hormones, growth factors, and cytokines. The importance of transcription factors of Smad family, of forkhead transcription factor (Fox) family, of breast cancer-associated genes/transcription factor, hypoxia-induced transcription factors and of other transcription factors in control of these processes has been demonstrated.

Intratubular germ cell neoplasia of the testis and its associated cancers: the use of novel biomarkers

Recent advances in the understanding of the molecular pathology of testicular tumours have led to the identification of several new immunohistochemical markers for invasive and in situ germ cell neoplasms. OCT3/4 and NANOG are nuclear stains that have high sensitivity and specificity for the identification of intratubular germ cell neoplasia as well as seminoma and embryonal carcinoma. A potential pitfall in their application to the detection of intratubular germ cell neoplasia, as in other markers that represent oncofetal antigens, is their expression in non-neoplastic germ cells with 'delayed maturation'. SALL4, another nuclear stain, is positive for most germ cell tumours as a group and may be especially helpful in the distinction of these tumours from somatic carcinomas in non-testicular sites. Glypican 3 is a more sensitive marker for yolk sac tumour than alpha-fetoprotein. SOX2 and SOX17 may be useful for differentiating seminoma and embryonal carcinoma, especially following chemotherapy as embryonal carcinoma may lose CD30 expression in this setting. This article reviews the application of these immunohistochemical markers and others to the diagnosis of germ cell neoplasia with reference to older immunohistochemical stains when appropriate. Suggested immunohistochemical panels are described for individual tumour types.

Morphologic, immunohistochemical, and fluorescence in situ hybridization study of ovarian embryonal carcinoma with comparison to solid variant of yolk sac tumor and immature teratoma

The prognosis and therapy for malignant ovarian germ cell tumors including embryonal carcinoma differ from those of other categories of ovarian tumors, making accurate diagnosis imperative for patient care. Because of its rarity, the protein markers and genomic alterations typifying primary ovarian embryonal carcinoma have not been fully characterized. The present study aims to establish a set of sensitive and specific protein markers useful for the diagnosis and delineation of ovarian embryonal carcinoma. Chromosomal 12p anomalies were analyzed by dual-color fluorescence in situ hybridization. In a series of 6 ovarian mixed germ cell tumors with a component of embryonal carcinomas, OCT4, CD30, SOX2, and glypican 3 expressions were analyzed immunohistochemically on formalin-fixed paraffin-embedded tissue specimens. The results were compared to 4 cases of mixed germ cell tumor that were originally mistaken for embryonal carcinoma. OCT4 marked the nuclei of 6 cases, among which 5 cases also showed glypican 3 expression indicative of an admixed yolk sac tumor component. SOX2 was positive in only 3 cases of embryonal carcinoma. In 1 case of mixed germ cell tumor containing embryonal carcinoma, embryoid bodies from a component of polyembryoma were demonstrated to be both OCT4 and CD30 positive. Two cases originally classified as embryonal carcinoma were OCT4 and CD30 negative and showed glypican 3 positivity. They were reclassified as solid variant of yolk sac tumor. Two other cases originally classified as embryonal carcinoma were OCT4 positive and CD30 negative and were classified as immature teratoma with neuroectodermal differentiation based on the immunohistochemical findings as well as morphologic features and were diagnosed as immature teratoma. Chromosome 12p alterations were identified in 5 of 6 cases of embryonal carcinomas. In summary, a panel of immunostains is more useful than a single biomarker in the differential diagnosis of ovarian germ cell tumors. Chromosome 12p fluorescence in situ hybridization combined with OCT4, CD30, and glypican 3 immunostains is useful in confirming the diagnosis of ovarian embryonal carcinoma.