Impact of the Y-containing cell line on histological differentiation patterns in dysgenetic gonads

Gender determination and long-time follow-up analysis of mixed gonadal dysgenesis

INTRODUCTION

Mixed gonadal dysgenesis (MGD) is a rare disorder of sexual development. The management of MGD is challenging since the disease significantly impacts a patient's growth, hormone balance, and gonadal development. This article used a large population and a long follow-up period for its analysis.

OBJECTIVES

This study aims to summarize the gender determination basis and analyze the long-term follow-up of mixed gonadal dysgenesis.

METHODS

A total of 45 patients' clinical data were summarized and analyzed. Patients were divided by gender. Next, we followed up regarding the occurrence of complications after surgery, the patients' satisfaction with external genitalia appearance, the growth of the patients, counting the surgical pattern the incidence of surgical complications and the development of the patients' growth. All patients included in this study underwent chromosomal karyotype analysis, abdomen exploration, and pathological biopsy. After sex determination, 7 patients who were raised as female underwent clitoroplasty, and bilateral gonadectomy. 38 male patients underwent urethroplasty + one-sided gonadectomy.

RESULTS

Patient follow-up started in the third month after surgery. Female patients reported no surgery-related complications, while 14 male patients showed surgery-related complications. Additionally, 20 male patients (60.6 %) had a lower height compared to normal peers, 12 of which (36.4 %) were lower than the second standard deviation of the height of normal peers.

CONCLUSION

The clinical manifestations of mixed gonadal dysgenesis are variable, and the management is complicated. Children's gonadal function, external genital conditions, psychological evaluation, and parents' wishes should be considered before sex determination. In China, most patients are raised as males with a high incidence of postoperative complications. We found that short stature is a common feature in male patients, thus their height and growth should be carefully supervised. Patients should pay attention to their sexual function and sexual potential during adulthood.

Clinical and Reproductive Characteristics of Patients with Mixed Gonadal Dysgenesis (45,X/46, XY)

Introduction

Mixed gonadal dysgenesis (MGD) or 45,X/46,XY mosaicism is a sex chromosomal disorder of sexual development. We aim to characterize the clinical and reproductive features of 45X/46 XY attending tertiary care center in Kerala.

Materials and Method

Retrospective review of clinical records which include clinical presentation, hormonal profile, cytogenetics, psychosexual assessment, and histopathology of gonadectomy specimen of ten cases of 45X/46 XY mosaicism who attended Endocrinology/ OBG out patient department from 2008 to 2020.

Results

The mean ages of all the cases were 12 ± 3.79 years (± 2 SD). Short stature was universally seen. Virilisation was the most common manifestation (80%) followed by delayed puberty (20%). Autoimmune thyroid disease was seen in 40% of cases. We noticed a delayed presentation in our clinical study. 45X/46 XY subjects who wished to continue as female underwent gonadectomy and were feminized with hormone replacement therapy. Male 45X/46 XY who retained their undescended testis is planned for periodic surveillance for malignancy.

Conclusion

45X/46 XY may present like Turner's syndrome in clinical practice. Early counseling and gender assignment by a panel of specialists are crucial. Delayed presentation is less commonly encountered now a day and may pose a clinical challenge. Management in 45X/46 XY is multi-disciplinary which includes Turner's like surveillance, proper sex assignment, timely genital reconstruction surgeries, gonadectomy, gonadal monitoring, and hormonal replacement therapy is needed.

Multidisciplinary Approach to the Child with Sex Chromosomal Mosaicism Including a Y-Containing Cell Line

Children born with sex chromosomal mosaicism including material derived from the Y chromosome may present with a broad phenotypical spectrum. Both boys and girls can present with Turner features and functional health problems typically associated with Turner syndrome, but the presence of Y-chromosomal material can modify some aspects of the condition. We retrospectively analyzed the results of our cohort of 21 individuals (14 boys, 7 girls) with sex chromosomal mosaicism including Y-derived material followed at Ghent University Hospital according to our local multidisciplinary Turner surveillance protocol. Results were compared with literature data, focusing on similarities and differences between girls and boys with this condition. Age at diagnosis was lower in boys compared to girls but the difference was not significant. Short stature is a key feature of the condition both in girls and boys, but skeletal maturation may be different between groups. The effects of growth-hormone therapy remain unclear. Cardiac (33%), ear-nose- throat (ENT) (77.8%) and renal (28.6%) problems were as prevalent in boys as in girls from our cohort, and did not differ from literature data. In line with literature reports, a significant difference in the presence of premalignant germ cell tumors between males (0%) and females (42.9%) was found (p = 0.026). Taken together, this study demonstrates the similarities between girls with Turner syndrome and children with sex chromosomal mosaicism including Y-derived material, regardless of the child’s gender. Nowadays, girls with Turner syndrome are offered a dedicated multidisciplinary follow-up in many centers. We advocate a similar follow-up program for all children who have sex chromosomal mosaicism that includes Y-derived material, with special attention to growth, cardiac and ear-nose-throat problems, gonadal function and malignancies.

Serum Concentrations and Gonadal Expression of INSL3 in Eighteen Males With 45,X/46,XY Mosaicism

OBJECTIVE

Insulin-like factor 3 (INSL3) is produced in the testes and has been proposed as a circulating biomarker of Leydig cell capacity, but remains undescribed in 45,X/46,XY mosaicism. The aim was to examine serum concentrations and gonadal expression of INSL3 in 45,X/46,XY mosaicism.

METHODS

Retrospectively collected data from medical records, gonadal tissue samples, and prospectively analyzed serum samples from eighteen male patients with 45,X/46,XY mosaicism (one prepubertal, four testosterone-treated, 13 untreated) were included. Biochemical, clinical, and histological outcomes were evaluated according to serum INSL3 concentrations, quantified by LC-MS/MS methodology, and gonadal INSL3 immunohistochemical expression.

RESULTS

Serum INSL3 concentrations spanned from below to above the reference range. In untreated patients, the median serum INSL3 SD score was -0.80 (IQR: -1.65 to 0.55) and no significant difference was observed between INSL3 and testosterone. There was no clear association between serum INSL3 and External Genitalia Score at diagnosis, spontaneous puberty, or sperm concentration. INSL3 and CYP11A1 expression overlapped, except for less pronounced INSL3 expression in areas with severe Leydig cell hyperplasia. No other apparent links between INSL3 expression and histological outcomes were observed.

CONCLUSIONS

In this pilot study, serum INSL3 concentrations ranged and seemed independent of other reproductive hormones and clinical features in males with 45,X/46,XY mosaicism. Discordant expression of INSL3 and CYP11A1 may explain low INSL3 and normal testosterone concentrations in some patients. Further studies are needed to elucidate the divergence between serum INSL3 and testosterone and the potential clinical use of INSL3.

Mediastinal germ cell tumors: many questions and perhaps an answer

Some germ cell tumors (GCTs) in men develop into hematologic malignancies; however, the clonal origins of such malignancies remain unknown. In this issue of the JCI, Taylor, Donoghue, et al. unravel the clonal relationship between primary mediastinal nonseminomas (PMNs) and hematologic somatic-type malignancies (HSTMs). Whole-exome sequencing was used to construct phylogenetic trees of the PMNs and the ensuing HSTM clones. HSTMs were derived from multiple distinct clones not detected within the PMNs. Clones from PMNs and HSTMs shared a common precursor, arguably an embryonal carcinoma cell resulting from a reprogrammed primordial germ cell from the thymus. Mutational and copy number variation analysis of a large cohort of patients with PMNs also demonstrated a high prevalence of TP53 mutations not found in testicular nonseminomas. These data likely explain why patients with PMNs are frequently resistant to platinum-based chemotherapy and provide TP53 mutations as potential targets.

Hemoptysis: A rare presentation of mixed gonadal dysgenesis

The objective of the study was to present a case report on a phenotypic male mixed gonadal dysgenesis (MGD) who presented with hemoptysis due to secondary lung metastasis from dysgerminoma. Phenotypic male MGD (45, X/46, XY) with primary infertility and hemoptysis participated in the study. This study was conducted at a tertiary care center. Laparoscopic visualization of gonads and presence of Müllerian/ Wolffian structures were ascertained. Gonadectomy of intra abdominal dysgenetic gonad were done. Fluorescence in situ hybridization analysis was done in gonadal tissue to find the presence of Y chromosome. Intra-abdominal gonad showed dysgerminoma changes. Müllerian structures in the form of rudimentary uterus and fallopian tubes were seen. Left inguinal gonad showed normal testicular structures. Chemotherapy for secondary lung metastasis contemplated.

Human germ cell tumours from a developmental perspective

Human germ cell tumours (GCTs) are derived from stem cells of the early embryo and the germ line. They occur in the gonads (ovaries and testes) and also in extragonadal sites, where migrating primordial germ cells are located during embryogenesis. This group of heterogeneous neoplasms is unique in that their developmental potential is in effect determined by the latent potency state of their cells of origin, which are reprogrammed to omnipotent, totipotent or pluripotent stem cells. Seven GCT types, defined according to their developmental potential, have been identified, each with distinct epidemiological and (epi)genomic features. Heritable predisposition factors affecting the cells of origin and their niches likely explain bilateral, multiple and familial occurrences of the different types of GCTs. Unlike most other tumour types, GCTs are rarely caused by somatic driver mutations, but arise through failure to control the latent developmental potential of their cells of origin, resulting in their reprogramming. Consistent with their non-mutational origin, even the malignant tumours of the group are characterized by wild-type TP53 and high sensitivity for DNA damage. However, tumour progression and the rare occurrence of treatment resistance are driven by embryonic epigenetic state, specific (sub)chromosomal imbalances and somatic mutations. Thus, recent progress in understanding GCT biology supports a comprehensive developmental pathogenetic model for the origin of all GCTs, and provides new biomarkers, as well as potential targets for treatment of resistant disease.

The Mosaicism Ratio of 45,X May Explain the Phenotype in a Case of Mixed Gonadal Dysgenesis

Some patients with mixed gonadal dysgenesis (MGD), whose prototypical karyotype is 45,X/46,XY, are known to manifest complications characteristic of Turner syndrome. We report a 16-year-old social male with MGD presenting with coarctation of the aorta, one of the common complications for Turner syndrome. At birth, the patient was found to have hypospadias, bifid scrotum, and cryptorchidism. Chromosomal analysis of his lymphocytes revealed the karyotype 45,X[7]/46,X,dic(Y;22)(p11.3;q13.3)[23] (named 45,X/46,X+Y fragment in this article). A left gonadectomy was performed at 1 year of age, and the histology showed a streak gonad with an epithelial cord-like structure compatible with MGD. At the age of 10 years, coarctation of the aorta was discovered by chance, for which the patient underwent surgical repair. The ratio of mosaicism in the gonad and aortic tissues was estimated by FISH with probes to identify the X centromere-specific repeat sequence and Yp11.2. The mosaicism ratio of 45,X/46,X+Y fragment varied among the tissues, with those having a higher ratio being more likely to exhibit the Turner syndrome phenotype. Some 90% of cells in the aortic tissues and 80% in the gonadal tissues lacked a Y chromosome. In conclusion, the mosaicism ratio in the different tissues may explain the phenotypes in MGD.

Pathogenesis of germ cell neoplasia in testicular dysgenesis and disorders of sex development

Development of human gonads is a sex-dimorphic process which evolved to produce sex-specific types of germ cells. The process of gonadal sex differentiation is directed by the action of the somatic cells and ultimately results in germ cells differentiating to become functional gametes through spermatogenesis or oogenesis. This tightly controlled process depends on the proper sequential expression of many genes and signalling pathways. Disturbances of this process can be manifested as a large spectrum of disorders, ranging from severe disorders of sex development (DSD) to - in the genetic male - mild reproductive problems within the testicular dysgenesis syndrome (TDS), with large overlap between the syndromes. These disorders carry an increased but variable risk of germ cell neoplasia. In this review, we discuss the pathogenesis of germ cell neoplasia associated with gonadal dysgenesis, especially in individuals with 46,XY DSD. We summarise knowledge concerning development and sex differentiation of human gonads, with focus on sex-dimorphic steps of germ cell maturation, including meiosis. We also briefly outline the histopathology of germ cell neoplasia in situ (GCNIS) and gonadoblastoma (GDB), which are essentially the same precursor lesion but with different morphological structure dependent upon the masculinisation of the somatic niche. To assess the risk of germ cell neoplasia in different types of DSD, we have performed a PubMed search and provide here a synthesis of the evidence from studies published since 2006. We present a model for pathogenesis of GCNIS/GDB in TDS/DSD, with the risk of malignancy determined by the presence of the testis-inducing Y chromosome and the degree of masculinisation. The associations between phenotype and the risk of neoplasia are likely further modulated in each individual by the constellation of the gene polymorphisms and environmental factors.

Identification of X monosomy cells from a gonad of mixed gonadal dysgenesis with a 46,XY karyotype: case report

Mixed gonadal dysgenesis (MGD) is a disorder of sexual development that typically has a mosaic 45,X/46,XY karyotype. A 1-year-old infant with 46,XY identified by peripheral blood karyotype demonstrated clinical manifestations and gonadal pathologic features of MGD. Fluorescence in situ hybridization (FISH) for X and Y chromosomes and immunofluorescence for SRY along with testicular and ovarian lineage markers SOX9 and FOXL2, respectively, were performed on paraffin sections from the gonad to ascertain the somatic mosaic state for 45,X monosomy and 46,XY cells. The gonad consisted of cells with X and XY signals, which were further quantified in comparison with a normal control testis by a digital image analysis program. The average percentages of 45,X cells of this patient's gonad and a control testis were 39.0% and 5.7%, respectively (χ2 test, P < 0.001). SRY expression was absent in approximately 10% of precursor granulosa cells (FOXL2 positive) and precursor Sertoli/granulosa cells (both SOX9 and FOXL2 positive) within gonadoblastomas, confirming the involvement of 45,X cells. A combination of analysis of FISH and immunofluorescence for SRY in the gonadal tissue could identify 45,X cells in MGD with 46,XY.

45,X/46,X,psu dic(Y) gonadal dysgenesis: influence of the two cell lines on the clinical phenotype, including gonadal histology

A child born with ambiguous genitalia (Prader III) was found to have a 45,X[92.2%]/46,X,psu dic(Y)(p12)[7.8%] karyotype in peripheral blood lymphocytes. The testosterone level was consistent with that of a normal male; however, gonadotropins were elevated. Ultrasound and endoscopy of the urogenital sinus revealed well-developed Müllerian structures. At 3.5 months, the child was operated for right-sided incarcerated hernia, and the gonad situated at the inguinal region was biopsied and classified as primitive testis. Based on the presence of Müllerian structures, anatomy of external genitalia and wish of the parents, the child was assigned female gender. She underwent removal of the left gonad at 4 months during another acute surgery; histology was similar to the right gonad. The rest of the right gonad was removed at 16 months, and feminizing genitoplasty took place at 3 years. The right and left gonad contained 28 and 22% of cells with a Y chromosome, respectively. During further histological examination, dysgenetic features of the gonads were discovered. Some germ cells displayed abnormal development based on the specific expression of immunohistochemical markers (OCT3/4, TSPY, KITLG), indicating a possible risk for future malignant germ cell tumor development. Contribution of the 45,X cell line to the phenotype was also observed: the patient developed celiac disease, and her growth pattern resembled that of Turner syndrome responding to growth hormone treatment.

SRY mutation analysis by next generation (deep) sequencing in a cohort of chromosomal Disorders of Sex Development (DSD) patients with a mosaic karyotype

Background

The presence of the Y-chromosome or Y chromosome-derived material is seen in 4-60% of Turner syndrome patients (Chromosomal Disorders of Sex Development (DSD)). DSD patients with specific Y-chromosomal material in their karyotype, the GonadoBlastoma on the Y-chromosome (GBY) region, have an increased risk of developing type II germ cell tumors/cancer (GCC), most likely related to TSPY. The Sex determining Region on the Y gene (SRY) is located on the short arm of the Y-chromosome and is the crucial switch that initiates testis determination and subsequent male development. Mutations in this gene are responsible for sex reversal in approximately 10-15% of 46,XY pure gonadal dysgenesis (46,XY DSD) cases. The majority of the mutations described are located in the central HMG domain, which is involved in the binding and bending of the DNA and harbors two nuclear localization signals. SRY mutations have also been found in a small number of patients with a 45,X/46,XY karyotype and might play a role in the maldevelopment of the gonads.

Methods

To thoroughly investigate the presence of possible SRY gene mutations in mosaic DSD patients, we performed next generation (deep) sequencing on the genomic DNA of fourteen independent patients (twelve 45,X/46,XY, one 45,X/46,XX/46,XY, and one 46,XX/46,XY).

Results and conclusions

The results demonstrate that aberrations in SRY are rare in mosaic DSD patients and therefore do not play a significant role in the etiology of the disease.

Undifferentiated gonadal tissue, Y chromosome instability, and tumors in XY gonadal dysgenesis

Patients with XY gonadal dysgenesis are at increased risk of developing gonadal tumors. The etiology of several cases of XY gonadal dysgenesis remains unknown, but X/XY gonadal mosaicism has been hypothesized to play a role. At the histologic level, the presence of persistent primitive sex cords containing immature germ cells in dysgenetic gonads (an entity called undifferentiated gonadal tissue, or UGT) was recently described, and these immature germ cells are thought to be at risk of neoplastic transformation. To further investigate both these aspects, we retrospectively studied the gonads from 30 patients with pure (22) and mixed (8) gonadal dysgenesis. Cytogenetic analyses performed on 35 gonads revealed that structurally abnormal Y chromosomes were lost in a majority of cells from the gonads, explaining the gonadal dysgenesis of patients bearing a rearranged Y chromosome. On the other hand, normal Y chromosomes were less often lost in gonads of patients with gonadal dysgenesis. At the histologic level, 43 of the 51 gonads presented areas characteristic of a streak; 13 of these streak gonads also presented areas of UGT. Structures resembling sex cords but without germ cells were found in many of the streaks not containing UGT, suggesting that UGT was initially present. Of the 13 gonads containing both UGT and a streak, 9 developed a tumor. The proximity of UGT with the tumors as well as the immunostaining patterns (PLAP+, OCT3/4+, and CD117/KIT+) suggests that germ cells found in UGT are a risk factor for gonadal tumors.

FOXL2 and SOX9 distinguish the lineage of the sex cord-stromal cells in gonadoblastomas

Gonadoblastomas are mixed germ cell sex cord-stromal tumors that arise in dysgenetic gonads and are composed of immature germ cells and sex cord-stromal cells of indeterminate differentiation. FOXL2 is one of the first genes expressed in female gonad development, and it is required for proper granulosa cell differentiation during folliculogenesis. SOX9 , a downstream target of SRY , the gene in the Y chromosomal sex-determining region, is required for testicular development and for the formation and maintenance of (pre-)Sertoli cells. This study characterized the sex cord-stromal cells of gonadoblastoma by evaluating the expression of these counteracting transcription factors. Archival paraffin-embedded material of 7 gonadoblastomas, 5 of which were overgrown by dysgerminoma, was examined by immunohistochemistry for expression and localization of FOXL2 and SOX9. The sex cord-stromal cells revealed strong nuclear staining for FOXL2 and were negative for SOX9 expression. Germ cells in the gonadoblastoma and dysgerminoma components showed no FOXL2 and SOX9 expression. Areas of transition between gonadoblastoma and dysgerminoma revealed nests with a gradual reduction of FOXL2 expression. Our results support the hypothesis that the sex cord-stromal cell component of gonadoblastomas is of granulosa cell origin. In addition, FOXL2 appears to be a useful marker for the evaluation of overgrowth by dysgerminomas and for the identification of the transition zone of "dysgerminoma in situ." As FOXL2 and SOX9 are differentially expressed, they also should be useful for distinguishing gonadoblastomas from intratubular germ cell neoplasias and can help to differentiate those with a Sertoli cell component from gonadoblastoma with a granulosa cell component.

Gonadal pathology and tumor risk in relation to clinical characteristics in patients with 45,X/46,XY mosaicism

CONTEXT

Gonadectomy is avoided whenever possible in boys with 45,X/46,XY. However, no clinical markers are currently available to guide clinicians in predicting gonadal tumor risk or hormone production.

OBJECTIVE

The objective of the study was to test the hypothesis that gonadal histology and risk for development of a malignant germ cell tumor are reflected by the clinical presentation of a 45,X/46,XY individual.

DESIGN

The design of the study was the correlation of clinical data [external masculinization score (EMS), pubertal outcome] with pathology data (gonadal phenotype, tumor risk).

SETTING

This was a multicenter study involving two multidisciplinary disorder of sex development teams.

PATIENTS

Patients included genetically proven 45,X/46,XY (and variants) cases, of whom at least one gonadal biopsy or gonadectomy specimen was available, together with clinical details.

INTERVENTIONS

Patients (n = 48) were divided into three groups, based on the EMS. Gonadal histology and tumor risk were assessed on paraffin-embedded samples (n = 87) by morphology and immunohistochemistry on the basis of established criteria.

MAIN OUTCOME MEASURES

Gonadal differentiation and tumor risk in the three clinical groups were measured. Clinical outcome in patients with at least one preserved gonad was also measured.

RESULTS

Tumor risk in the three groups was significantly related to the gonadal differentiation pattern (P < 0.001). In boys, hormone production was sufficient and was not predicted by the EMS.

CONCLUSIONS

The EMS reflects gonadal differentiation and tumor risk in patients with 45,X/46,XY. In boys, testosterone production is often sufficient, but strict follow-up is warranted because of malignancy risk, which appears inversely related to EMS. In girls, tumor risk is limited but gonads are not functional, making gonadectomy the most reasonable option.

Dysgerminoma and gonadal dysgenesis: the need for a new diagnosis tree for suspected ovarian tumours

PURPOSE

Diagnosis of dysgerminoma in the paediatric age group is uncommon, and most cases arise from dysgenetic gonads of 46, XY pure gonadal dysgenesis (PGD) patients. Bilateral gonadectomy is mandatory in these patients. So, the preoperative diagnosis of PGD is important in order to avoid multiple surgical procedures and delayed patient information in the case of a suspected 'ovarian' tumour. Our aim was to discuss preoperative clues that can lead to suspicion of dysgerminoma in the context of PGD.

MATERIALS AND METHODS

We reviewed the charts of six patients treated for dysgerminoma associated with 46, XY PGD. We focused on particularities of clinical and biological evaluations.

RESULTS

Median age at diagnosis was 11 years. Pubertal development was absent or incomplete even at late ages. Dysgerminoma was associated with gonadoblastoma foci in all cases. Tumoral marker profile was a normal alfafetoprotein level, a high lactate dehydrogenase level and normal or moderate human chorionic gonadotropin (βHCG) secretion, except for one patient who had a mixed tumour with notably a choriocarcinoma share (high βHCG). Follicle-stimulating hormone (FSH) level was very high in all patients tested and, interestingly, also in one prepubertal patient.

CONCLUSIONS

In the case of a suspected ovarian tumour, delayed pubertal development, moderate βHCG level and elevated FSH level are clinical and biological clues to a diagnosis of dysgerminoma in the context of PGD and should prompt karyotype analysis before surgery. Because FSH is an efficient indirect marker of this condition, we suggest including this analysis in the management of gonadal tumours.

46,XY pure gonadal dysgenesis: clinical presentations and management of the tumor risk

PATIENTS

Eleven patients with 46,XY PGD were divided into two groups. Six symptomatic girls (group 1) were referred for amenorrhea (n = 3), gonadal tumor (n = 2) or campomelic dysplasia (n = 1). Five asymptomatic screened patients (group 2) were diagnosed as 46,XY PGD after familial investigation of the two probands with gonadal tumor. Bilateral gonadectomy was performed in all patients.

RESULTS

In group 1, pathologic examination revealed an association of dysgerminoma with gonadoblastoma (n = 2), bilateral gonadoblastoma (n = 2) and streak gonads (n = 2). Prophylactic gonadectomy in asymptomatic patients (group 2) also showed asymptomatic dysgerminoma with gonadoblastoma (n = 1), bilateral gonadoblastoma (n = 2) and streak gonads (n = 2).

CONCLUSIONS

A gonadal tumor arising in a girl with pubertal delay may be related to dysgenesis of the gonad. Primary amenorrhea or diagnosis of dysgerminoma should warrant karyotype, and familial study if 46,XY PGD is found. Considering the high incidence of gonadoblastoma and the early occurrence of dysgerminoma, early bilateral gonadectomy is recommended.

Gonadal tumours and DSD

Disorders of sex development (DSD), previously referred to as intersex, has been recognised as one of the main risk factors for development of type II germ cell tumours (GCTs), that is, seminomas/dysgerminomas and non-seminomas (e.g., embryonal carcinoma, yolk sac tumour, choriocarcinoma and teratoma). Within the testis, this type of cancer is the most frequent malignancy in adolescent and young adult Caucasian males. Although these males are not known to have dysgenetic gonads, the similarities in the resulting tumours suggest a common aetiological mechanism(s),--genetically, environmentally or a combination of both. Within the group of DSD patients, being in fact congenital conditions, the risk of malignant transformation of germ cells is highly heterogeneous, depending on a number of parameters, some of which have only recently been identified. Understanding of these recent insights will stimulate further research, with the final aim to develop an informative clinical decision tree for DSD patients, which includes optimal (early) diagnosis without overtreatment, such as prophylactic gonadectomy in the case of a low tumour risk.

New insights into type II germ cell tumor pathogenesis based on studies of patients with various forms of disorders of sex development (DSD)

Disorders of sex development (DSD), previously known as intersex, refer to congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical. Patients with specific variants of this disorder have an elevated risk for the development of so-called type II germ cell cancers, i.e., the seminomatous and nonseminatous tumors, referred to as germ cell tumors (GCTs). Specifically DSD patients with gonadal dysgenesis or hypovirilization are at risk. A prerequisite for type II GCT formation is the presence of a specific part of the Y chromosome (referred to as the GBY region), with the TSPY gene being the most likely candidate. Also the octamer binding transcription factor OCT3/4 is consistently expressed in all type II GCTs with pluripotent potential, as well as in the precursor lesions carcinoma in situ (CIS) in case of a testis and gonadoblastoma (GB) in the DSD gonad. The actual risk for malignant transformation in individual DSD patients is hard to predict, because of confusing terminology referring to the different forms of DSD, and unclear criteria for identification of the presence of malignant germ cells, especially in young patients. This is specifically due to the phenomenon of delay of germ cell maturation, which might result in over diagnosis. This review will give novel insight into the pathogenesis of the type II GCTs through the study of patients with various forms of DSD for which the underlying molecular defect is known. To allow optimal understanding of the pathogenesis of this type of cancers, first normal gonadal development, especially regarding the germ cell lineage, will be discussed, after which type II GCTs will be introduced. Subsequently, the relationship between type II GCTs and DSD will be described, resulting in a number of new insights into the development of the precursor lesions of these tumors.