DNA content of ovarian immature teratomas and malignant germ cell tumors

Delayed DNA replication in haploid human embryonic stem cells

Haploid human embryonic stem cells (ESCs) provide a powerful genetic system but diploidize at high rates. We hypothesized that diploidization results from aberrant DNA replication. To test this, we profiled DNA replication timing in isogenic haploid and diploid ESCs. The greatest difference was the earlier replication of the X Chromosome in haploids, consistent with the lack of X-Chromosome inactivation. We also identified 21 autosomal regions that had delayed replication in haploids, extending beyond the normal S phase and into G2/M. Haploid-delays comprised a unique set of quiescent genomic regions that are also underreplicated in polyploid placental cells. The same delays were observed in female ESCs with two active X Chromosomes, suggesting that increased X-Chromosome dosage may cause delayed autosomal replication. We propose that incomplete replication at the onset of mitosis could prevent cell division and result in re-entry into the cell cycle and whole genome duplication.

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.

Lessons from human teratomas to guide development of safe stem cell therapies

The potential for the formation of teratomas or other neoplasms is a major safety roadblock to clinical application of pluripotent stem cell therapies. Preclinical assessment of the risk of tumor formation in this context poses considerable scientific and regulatory challenges, especially because animal xenograft models may not properly reflect the long-term tumorigenic potential of human cells. A better understanding of the biology of spontaneously occurring teratomas and related tumors in humans can help to guide efforts to assess and minimize the potential hazards of embryonic stem cell or induced pluripotent stem cell therapeutics. Here we review the features of teratomas derived experimentally from human pluripotent stem cells and argue that they most closely resemble spontaneous benign teratomas that occur early in both mouse and human life. The natural history and pathology of these spontaneously occurring teratomas provide important clues for preclinical safety assessment and patient monitoring in trials of stem cell therapies.

Gonadoblastoma: Case report of two young patients with isochromosome 12p found in the dysgerminoma overgrowth component in one case

Gonadoblastomas are unusual neoplasias that frequently appear in the dysgenetic gonads of women with chromosome Y anomaly. We present two cases of gonadoblastoma associated with complete gonadal dysgenesis and Turner syndrome, respectively, with dysgerminoma overgrowth found in one case. We were interested in the DNA ploidy, the presence of Y chromosome DNA sequence and the status of chromosome 12p arm among the tumor cells. We performed cytophotometry to analyze the DNA content and fluorescence in situ hybridization (FISH) to identify the Y chromosome and the isochromosome 12p within the tumor cells. The cytophotometric result showed diploid DNA content in gonadoblastoma, whereas dysgerminoma revealed aneuploid DNA. The FISH result revealed Y chromosome DNA sequence within gonadoblastoma and dysgerminoma. Isochromosome 12p was identified in dysgerminoma, but not in gonadoblastoma. We conclude that gonadoblastoma and dysgerminoma have a strong association with the Y chromosome, and dysgerminoma overgrowth is due to further chromosomal aberrations, such as isochromosome 12p. Histological, immunohistocheimcal and molecular studies should render the correct diagnosis. Identifying dysgerminoma overgrowth is crucial since it is associated with adverse prognosis and requires additional therapy.

[The ovarian immature teratoma with gliomatosis peritonei]

OBJECTIVE

We return a case of ovarian immature teratoma with peritoneal gliomatose at a woman aged of 20 years.

MATERIAL AND METHODS

The diagnosis discovered following pelvic mass increasing volume and treaty by a one-sided annexectomy, with chemotherapy.

RESULTS

Eighty-seven cases have been published in the literature. Although potential for recurrence is high, the risk of malignancy is very low.

CONCLUSION

Ovarian immature teratoma is a malignant germ cell tumor and represents less than 1% of ovarian malignant tumors. Tissues are derived from the three germ layers (endo-, meso- and ectoderm). Tumor grading is based on the amount of immature neuroepithelium present. The prognosis is directly correlated to histological grade. Rapid (fast) growth leads to large tumors with an early diagnosis. Gliomatosis peritonei is a rare situation, characterized by the recurrence of peritoneal implants after the surgical treatment of ovarian teratoma. This entity does not modify the good prognosis of mature teratomas, but we recommend regular follow-up.

An ovarian dysgerminoma in Down syndrome. Hypothesis about the association

An 11-year-old girl with Down syndrome (DS) was operated for a stage I right ovary dysgerminoma. She is in good health 33 years later. Some data in the literature suggest that ovarian cancers could be slightly overrepresented in DS. Despite the rarity of ovarian dysgerminoma, our case is the fifth reported in DS. This case is the second one associated with a family history suggesting the possibility of a familial predisposition to cancer. A hypothesis explaining the development of dysgerminoma in DS is proposed.

Analysis of ovarian teratomas for isochromosome 12p: evidence supporting a dual histogenetic pathway for teratomatous elements

Teratomas are the most common germ cell tumor (GCT) of the ovary and include several types with a range of clinical behavior. As in testicular teratomas, they may be benign, malignant or a component of a mixed GCT. In the testis, data support separate pathogeneses for prepubertal and postpubertal teratomas, with derivation of the former from a nontransformed germ cell and the latter from differentiation of a nonteratomatous, malignant GCT. The absence of cytogenetic abnormalities (including isochromosome 12p (i(12p)) in mature ovarian teratomas suggests that they may be analogous to prepubertal testicular teratomas, but there are no data regarding genetic changes in the teratomatous components of ovarian mixed GCTs. We therefore studied the teratomatous components of six mixed GCTs of the ovary using fluorescence in situ hybridization (FISH) for i(12p). Six mixed GCTs of the ovary occurred in patients 4-33 years of age; all had teratomatous and yolk sac tumor components and three also contained foci of embryonal carcinoma. Using FISH with 12p telomeric and 12 centromeric probes, five of six (83%) cases had detectable i(12p) in their nonteratomatous components, and four of six (66%) in the teratomatous component. One of the two cases without demonstrable i(12p) in the teratomatous portion of the mixed GCT also did not have identifiable 12p abnormalities in other elements of the mixed GCT. By comparison, five pure, mature ovarian teratomas and three pure, immature ovarian teratomas showed no evidence of either i(12p) or other forms of 12p amplification. These findings support that teratoma in mixed ovarian GCTs has a different pathogenesis compared to pure teratoma of the ovary. Furthermore, the findings of i(12p) in both the teratomatous and nonteratomatous components of ovarian mixed GCTs supports that the teratoma derives from other components, similar to the situation in the testis.

Malignant germ cell tumors in childhood

Malignant germ cell tumors are a very heterogeneous group of neoplasms that have historically carried a poor prognosis. A review of the cooperative studies on malignant extracranial germ cell tumors in children was performed to update the progress in treatment and outcome for this rare group of tumors. The advent of platinum-based chemotherapy in the 1980s dramatically improved the prognosis for these tumors and allowed redefinition of risk groups. Chemotherapy regimens have been sequentially modified to reduce toxicity while maintaining survival. Surgical management has evolved from an aggressive en bloc resection at diagnosis to a more tailored approach, with resection and meticulous staging for low stage tumors at diagnosis and biopsy with neoadjuvant chemotherapy for advanced stage tumors. Improved surgical margins and prognosis are seen in post chemotherapy resections for high stage tumors. Large persisting masses after chemotherapy are often due to coexisting elements of benign teratoma, and aggressive attempts at resection are warranted in these patients with expectation of successful outcome.

Evaluation of genomic changes in a large series of malignant ovarian germ cell tumors—relation to clinicopathologic variables

Malignant ovarian germ cell tumors (mOGCT) affect women in their reproductive years, making fertility-saving treatment important. A reliable prediction of the clinical behavior is essential for an optimal therapeutic approach. The genetic changes and molecular mechanisms underlying these rare tumors remain poorly understood. To address these issues, we performed DNA ploidy analysis by high-resolution image cytometry in a series of 47 mOGCT and correlated the findings with the DNA copy number changes detected by comparative genomic hybridization (CGH) and clinical outcome. Of 47 tumors, 15 were diploid, 14 were tetraploid, 2 were polyploid, and 13 were aneuploid. All the immature teratomas were diploid, in contrast to the dysgerminomas and endodermal sinus tumors. The International Federation of Gynecology and Obstetrics (FIGO) staging, residual tumors after surgery, and DNA ploidy distribution were significant, independent prognostic factors in survival analysis. The study revealed that the number of DNA copy number aberrations was increased in tetraploid and aneuploid tumors as compared to diploid tumors. Furthermore, a high percentage of aneuploid nuclei in a sample were associated with a complex CGH profile of the tumor in question. The present study confirms that DNA aneuploidy assessment by image analysis may be linked to genetic instability, which is detected as genetic aberrations by CGH. DNA ploidy gives significant prognostic information in addition to the clinical stage in mOGCT with FIGO stage II-IV.

Gonadal teratomas: a review and speculation

Teratomas of the ovary and testis are confusing because, despite histologic similarities, they exhibit different biologic behaviors, depending mostly on the site of occurrence and the age of the patient. Thus, most ovarian teratomas are benign, and most testicular teratomas are malignant, with the exception of those occurring in children. These general statements, however, do not hold true for ovarian teratomas that are "immature" or exhibit "malignant transformation" and for dermoid and epidermoid cysts of the testis, categories of ovarian and testicular teratomas that are malignant and benign, respectively. This review concentrates on some of the "newer" observations concerning these interesting and confusing neoplasms, including diagnostically deceptive patterns. It is the author's opinion that much of the confusion regarding gonadal teratomas can be clarified by the concept that the usual ovarian teratoma derives from a benign germ cell in a parthenogenetic-like fashion, whereas the typical postpubertal testicular example derives from a malignant germ cell, mostly after evolution of that originally malignant cell to an invasive germ cell tumor (ie, embryonal carcinoma, yolk sac tumor, etc). The postpubertal testicular teratomas can therefore be thought of as an end-stage pattern of differentiation of a malignant germ cell tumor. The pediatric testicular teratomas, as well as dermoid and epidermoid cysts of the testis, however, must derive from benign germ cells, in a fashion similar to most ovarian teratomas. The teratomatous components of mixed germ cell tumors of the ovary, on the other hand, likely have a pathogenesis similar to that of postpubertal testicular teratomas.

Germ cell tumours in neonates and infants: a distinct subgroup?

Human germ cell tumours (GCTs) constitute a heterogeneous group of tumours that can be classified into four major subgroups. One of these subgroups encompasses (immature) teratomas and yolk sac tumours of patients under the age of 5 years. In this paper we review the various clinical, histological and cytogenetical aspects of these infantile GCTs. The primordial germ cell (PGC) has been suggested to be the cell of origin for GCTs. Infantile GCTs, however, have been suggested to originate from PGCs at a different stage of maturation than adult GCTs. The cytogenetic constitution of infantile GCTs also appears to differ from the adult GCTs and includes recurrent losses of lp and 6q. Recently, two cases of infantile GCT were detected with constitutional 12q13 translocations. These exceptional cases may be instrumental in the search for candidate genes related to infantile and/or adult GCT development.

Disseminated choriocarcinoma in infancy is curable by chemotherapy and delayed tumour resection

Infantile choriocarcinoma has a poor prognosis with only 2 surviving children reported in the literature. 2 additional successfully treated children are presented. 2 infants (age 3 and 4 months at diagnosis) suffering from rapidly progressive choriocarcinoma with widespread haematogenous metastases involving the liver were treated according to the cooperative germ cell tumour treatment protocol (MAKEI 96) of the German Society of Pediatric Oncology and Hematology (GPOH). PEI-chemotherapy (cisplatin, etoposide, ifosfamide; no ifosfamide before the age of 4 months) was combined with delayed tumour resection. Treatment resulted in sustained remission in both children (event-free survival 42 and 40 months). Interphase fluorescent in situ hybridisation (FISH) analysis of the paraffin-embedded tumour sample from case one revealed four to eight copies of chromosomes X, 1 and 17 and two Y chromosomes. Hybridisation with sub-telomere and centromere specific probes for chromosome 1 displayed an imbalance between the short and long arms of chromosome 1. In the tumour cells from case 2, only a polysomy of chromosome X could be proven, other aberrations were not analysed in this case for technical reasons.

DNA ploidy analysis and cell proliferation in congenital sacrococcygeal teratomas

BACKGROUND

Congenital sacrococcygeal teratoma is the most common germ cell tumor in infants and children. It usually is diagnosed at birth, is benign, and consists of fully differentiated mature tissues. Congenital sacrococcygeal teratomas (SCTs) also may contain immature tissues, most commonly of neural origin. The proportion of malignant teratomas increases with advancing age, but the relation between mature and immature SCTs is not well understood. Thus, it is very important to determine proliferative activity, DNA ploidy, and DNA index to predict biologic behavior of these tumors.

METHODS

DNA ploidy and cell proliferation were analyzed by flow cytometry, and the expression of proliferating cell nuclear antigen (PCNA) and Ki-67 were analyzed immunohistochemically on paraffin embedded tissue.

RESULTS

All the tumors that were surgically treated within 3 months after birth, including immature teratoma, were diploid. Strongly positive PCNA immunostaining was found in both immature teratomas, and weakly positive PCNA was found in nine cases. Weak positivity for Ki-67 was observed in 2 cases, and moderate positivity was observed in 6 cases including immature teratomas.

CONCLUSION

The value of flow cytometry in the prediction of biologic behavior of congenital SCT should be analyzed further. Our results suggest that Ki-67 and especially PCNA may reflect the proliferative activity of these tumors.