Oncofetal protein glypican-3 in testicular germ-cell tumor

The expression of an oncofetal protein, the glypican-3 (GPC3), was immunohistochemically evaluated in a wide variety of primary testicular germ-cell tumors (GCTs) in comparison with other markers, alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG)-beta, and OCT3/4. Eighty-nine cases of GCT including 22 cases of mixed GCT were evaluated with reference to each tumor component. GPC3 expression was observed in neoplastic cells of yolk-sac tumor (YST) (25/25), teratoma (2/10), components of syncytiotrophoblastic giant cells (STGCs) (10/14), and choriocarcinoma (1/3), but none in intratubular germ-cell neoplasias, unclassified type (0/33), seminomas (0/61), or embryonal carcinoma (0/19). All cases of YST showed diffuse labeling of neoplastic cells in cytoplasmic and membranous patterns, and the positive area of GPC3 was much larger than that of AFP. Glandular structures in teratomas showed GPC3 immunostaining as well as AFP. Although the number of GPC3-positive cells was smaller in STGC components and choriocarcinoma, there was no diffusion artifact in GPC3 immunostaining, as was frequently encountered in hCG-beta staining. Thus, GPC3 is a unique oncofetal protein, which is useful as an immunohistochemical marker for GCT differentiated to extraembryonic tissue, especially YST.     

Molecular genetic evidence supporting diverse histogenic origins of germ cell tumors

Germ cell tumors (GCTs) originate during the histogenesis of primordial germ cells to mature gametes. Previous studies identified five histogenic mechanisms in ovarian mature teratomas (type I: failure of meiosis I; type II: failure of meiosis II; type III: duplication of the genome of a mature gamete; type IV: no meiosis; and type V: fusion of two different ova), but those of other GCTs remain elusive. In this study, we analyzed 84 GCTs of various pathologic types to identify the histogenesis using single-nucleotide polymorphism array by analyzing copy-neutral loss of heterozygosity (CN-LOH) and copy number alterations (CNAs). We detected types I and II in ovarian teratomas, type III in ovarian teratomas and yolk sac tumors (YSTs), and type IV in all GCT types. The GCTs with multiple-type histogenesis (I–IV) (ovarian mature/immature teratomas and YST) show meiotic CN-LOH with scant CNAs. Type IV-only GCTs are either with mitotic CN-LOH and abundant CNAs (seminoma, dysgerminoma, testicular mixed GCTs) or with scant CNAs and no CN-LOH (pediatric testicular and mediastinal teratomas). The development sequences of CN-LOH and CNA are different between the multiple type (I–IV) GCTs and type IV-only GCTs. We analyzed two different histologic areas in eight GCTs (one mature teratoma with a mucin-secreting adenoma, two immature teratomas, and five mixed GCTs). We found that GCTs (mature teratoma, immature teratoma, and mixed GCT) showed different genomic alterations between histologic areas, suggesting that genomic differences within a GCT could accompany histologic differentiation. Of note, we found evidence for collision tumors in a mixed GCT. Our data indicate that GCTs may have various histogenesis and intratumoral genomic differences, which might provide important information for the identification of GCTs, especially for those with different histologic areas. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Expression of glypican 3 in ovarian and extragonadal germ cell tumors

Germ cell tumors (GCTs), rare malignancies that occur in a wide range of locations and display variable histologic patterns, may pose diagnostic challenges. Glypican 3 (GPC3), a membrane-bound heparan sulfate proteoglycan, has been shown to be a novel diagnostic marker in testicular GCT. However, GPC3 expression in ovarian and extragonadal GCT has not been reported. We evaluated GPC3 immunoreactivity in GCTs from 63 patients (57 children and 6 adults), including 14 ovarian and 20 extragonadal primary GCTs and 8 metastases along with 21 primary testicular GCTs for comparison. All 33 yolk sac tumors (YSTs) and both choriocarcinomas were immunoreactive for GPC3. In contrast, a minority of immature (4/10) and mature (4/35) teratomas were positive. No positivity was seen in 6 embryonal carcinomas or 5 germinomas. GPC3 is differentially expressed in ovarian and extragonadal GCTs, with expression predominantly observed in YSTs and choriocarcinoma.     

Hypermethylation of the RUNX3 gene promoter in testicular yolk sac tumor of infants

Testicular yolk sac tumor (YST) of infants is biologically distinct from its adult counterpart. Cytogenetically, YSTs in infants generally lack i(12p), which is highly characteristic of adult germ cell tumors (GCTs), whereas they frequently show a deletion of 1p36, indicating that the loss of a certain gene(s) in this region is an important event in the pathogenesis of infantile YSTs. In the present study, we examined 10 testicular YSTs from infants for promoter methylation status of the RUNX3 gene, localizing in 1p36.1, and loss of heterozygosity (LOH) in this region, on the presumption that RUNX3 acts as a tumor suppressor. Methylation of RUNX3 and LOH at 1p36.1 were detected in 8 of 10 (80%) and 6 of 8 (75%) infantile YSTs examined, respectively. All six cases harboring LOH showed RUNX3 methylation. In contrast, 0 of 12 adult GCTs showed RUNX3 methylation, and LOH at 1p36.1 was less frequent (1 of 6 cases: 16%) in adult GCTs. There is a significant difference in RUNX3 methylation between these 2 groups (P < 0.001). In normal testes of the young group, RUNX3 methylation was not detected. These results strongly suggest that RUNX3 is one of the tumor suppressors involved in the pathogenesis of testicular YSTs in infants.     

Expression pattern of clinically relevant markers in paediatric germ cell- and sex-cord stromal tumours is similar to adult testicular tumours

Paediatric germ cell tumours (GCTs) are rare and account for less than 3 % of childhood cancers. Like adult GCTs, they probably originate from primordial germ cells, but the pattern of histopathological types is different, and they occur predominantly in extragonadal sites along the body midline. Because they are rare, histology of paediatric GCTs is poorly documented, and it remains unclear to what extent they differ from adult GCTs. We have analysed 35 paediatric germ cell tumours and 5 gonadal sex-cord stromal tumours from prepubertal patients aged 0–15 years, to gain further knowledge, elaborate on clinical-pathological associations and better understand their developmental divergence. The tumours were screened for expression of stemness-related factors (OCT4, AP-2γ, SOX2), classical yolk sac tumours (YSTs; AFP, SALL4), GCTs (HCG, PLAP, PDPN/D2-40), as well as markers for sex-cord stromal tumour (PDPN, GATA4). All YSTs expressed AFP and SALL4, with GATA4 present in 13/14. The majority of teratomas expressed SOX2 and PDPN, whereas SALL4 was found in 8/13 immature teratomas. Adult seminoma markers AP-2γ, OCT4, SALL4 and PDPN were all expressed in dysgerminoma. We further report a previously unrecognised pathogenetic relationship between AFP and SALL4 in YST in that different populations of YST cells express either SALL4 or AFP, which suggests variable differentiation status. We also show that AP-2γ is expressed in the granulosa layer of ovarian follicles and weakly expressed in immature but not in mature granulosa cell tumours. Our findings indicate that the expression pattern of these antigens is similar between paediatric and adult GCTs, even though they develop along different developmental trajectories.     

Germ-cell tumors of the mediastinum.

Mediastinal germ-cell tumors (GCTs) usually occur within the anterior mediastinum, accounting for about 15% of all mediastinal cysts and tumors. They are associated with the thymus, presumably arising from extragonadal germ cells or thymic cells with germ-cell potential. Mediastinal seminoma develops primarily in young males with rare cases reported in females; likewise, embryonal carcinoma, endodermal sinus tumor or yolk-sac tumor, choriocarcinoma, and malignant mixed or combined GCTs also overwhelmingly affect males. Mature cystic teratoma affects males and females equally. The prognosis for mediastinal mature cystic teratoma and seminoma is very good. Nonseminomatous malignant GCTs of the mediastinum often present with advanced disease and do not respond as well to chemotherapy as their gonadal counterparts. Nonetheless, it is important to separate mediastinal GCTs from other undifferentiated malignant tumors, especially thymic carcinoma, which has a poor prognosis. Clearly, some patients with mediastinal GCTs respond very well to modern therapies.     

Primary juxtaovarian yolk sac tumor concurrent with an ipsilateral ovarian mature teratoma in an adult woman: a rare association

Objectives: Yolk sac tumor (YST) is a rare neoplasm that primarily occurs in the ovary in children and young women. Previously, it has been reported that the teratomatous components can be recognized in part of YSTs or appear in the contralateral ovary. Here, we report a rare case of an adult woman with a juxtaovarian YST concurrent with an ipsilateral ovarian mature teratoma. Methods: A 47-year-old woman found a pelvic mass for nine days and subsequently underwent debulking operation. The specimens were evaluated for detailed characterizations through gross examination, microscopy and immunohistochemistry. A literature review was performed and the pathogenesis was briefly discussed about the generation of an extraovarian YST concurrent with a teratoma. Results: The right juxtaovarian tumor showed typical histological patterns of YST. Immunostaining demonstrated the YST nature of Gly-3 and AFP positive tumor cells. The ipsilateral ovarian tumor was a common mature cystic teratoma with chronic fibrotic changes. According to the differences of the origin and the differentiation of the two germ cell tumors, we suspect that the occurrence of the teratoma is earlier than the YST. Conclusions: To our knowledge, this is the first report of an adult woman with a juxtaovarian YST concurrent with an ipsilateral ovarian mature teratoma.     

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.     

Angiosarcoma masquerading as embryonal carcinoma in the metastasis from a mature testicular teratoma

Sarcoma can arise within a germ cell tumor (GCT) from a malignant transformation of teratomatous elements or as late sequelae to radiation therapy. Angiosarcoma as a malignant component in testicular GCTs has rarely been reported and is often misdiagnosed as embryonal carcinoma. We report the case of a 23-year-old man with mature teratoma of the testis and retroperitoneal metastasis exhibiting components of mature teratoma intermingled with high-grade angiosarcoma. It is important to recognize the presence of a high-grade sarcomatous component within a GCT because of its aggressive clinical behavior and different response to therapy.     

Extragonadal germ cell tumors: A fine-needle aspiration biopsy study

Germ cell tumors (GCT) are neoplasms that originate predominately in the ovary and testis. Tumors of germ cell origin only very uncommonly arise in extragonadal sites. We have diagnosed ten primary malignant extragonadal GCT arising in the mediastinum, retroperitoneum, liver, and sacrococcygeal region by fine-needle aspiration biopsy (FNAB). Patient ages ranged from 1 to 54 years; the majority were males. Our series included three seminomas, three yolk sac tumors (YST), one choriocarcinoma, one embryonal carcinoma, and two mixed, poorly differentiated GCT. in aspirates, seminomatous elements are dissociated with uniform mononucleate cells having large vesicular nuclei and prominent nucleoli. A tigroid background is produced with Diff-Quik—stained smears. YST yields cohesive clusters of cells with large nuclei, vacuolated cytoplasm, and extracellular hyaline matrix (spheres or hyaline globules). Giant multinucleate tumor cells are seen in choriocarcinoma. Embryonal carcinoma yields cellular smears of hyperchromatic cells with scant cytoplasm arranged predominantly in glandular or papillary formations. Ultrastructural (four cases) and immunocytochemical (seven cases) studies of aspirated material corroborated our cytologic interpretations. Aneuploid tumor cells were found by flow cytometry in aspirated material from a YST. Subsequent histologic examinations were performed on eight, and all were confirmatory. Although extragonadal GCT are relatively uncommon, they need to be considered in FNAB material from midline mass lesions. Ancillary studies were useful in confirming their diagnosis. © Wiley-Liss, Inc.     

Cytogenetic and molecular analysis of human male germ cell tumors: chromosome 12 abnormalities and gene amplification

We report karyotypic analysis of 24 male germ cell tumors (GCTs) with clonally abnormal karyotypes biopsied from testicular and extragonadal lesions from 20 patients belonging to the histologic categories seminoma, teratoma, embryonal carcinoma, choriocarcinoma, and endodermal sinus tumor. Chromosomes 1, 7, 9, 12, 17, 21, 22, and the X chromosome were nonrandomly gained in these tumors. Nonrandom structural changes affected most frequently chromosomes 1 and 12, the latter as i(12p) and/or del(12)(q13----q22). The i(12p) was seen in 90% of tumors which included all histologic subtypes and gonadal as well as extragonadal presentation. Our present results, along with those from published data on fresh GCT biopsies, establish that i(12p) is a highly nonrandom chromosome marker of all histologic as well as anatomic presentations of GCTs. in contrast, we found del(12)(q13----q22) exclusively in nonseminomatous GCTs (NSGCTs) and mixed GCTs (MGCTs) occurring in 44% of such lesions. Because successful cytogenetic analysis of fresh tumor specimens is not always possible, we developed a method based on DNA analysis to detect i(12p) as increased copy number of 12p. In addition to the changes affecting chromosome 12 identified above, we have detected, for the first time, cytological evidence of gene amplification in the form of homogeneously staining regions (HSRs) and double minute chromosomes (dmins) in treated as well as untreated primary extragonadal and metastatic GCTs and confirmed the presence of amplified DNA in one of these tumors at the molecular level by the in-gel renaturation method. Hybridization of DNA from cultured cells from an HSR-bearing tumor with a panel of probes for genes known to be amplified or otherwise perturbed in diverse tumor systems did not identify the amplified gene, suggesting amplification of a novel gene or genes. This study comprises the largest series of GCT cytogenetics attempted so far. Notably, it includes data on a series of primary mediastinal tumors, a group which previously has not been studied in any detail.     

Pure post-pubertal yolk sac tumor of the testis: An extremely rare and aggressive entity

ContextPure post-pubertal yolk sac tumors (YSTs) are an extremely rare type of malignant germ cell tumor (GCT) that account for <1 % of testicular GCTs. Clinically, they are more aggressive compared to the more common pre-pubertal counterpart. The aim of this study is to analyze the clinical presentation, ancillary tests and clinical outcomes in addition to presenting a spectrum of histomorphological features, in a case series along with a literature review.DesignA retrospective review of 4 cases of pure post-pubertal YST of the testis was performed.Data collected for each patient included demographics, clinical presentation, serum markers, radiology and pathologic findings, treatment, and clinical outcomes.ResultsAll patients presented with a testicular mass with or without associated pain and elevated serum alpha-feto protein. Mean age at presentation was 36 years (range 25–68 years). Two patients presented with metastatic disease at the time of diagnosis. Histologic patterns and features are as follows: germ cell neoplasia in-situ (n = 4), reticular/microcystic, solid, glandular, papillary, endometrioid, cystic, necrosis and angiolymphatic invasion (n = 3). Fluorescent in-situ hybridization test performed on Case 2, showed presence of isochromosome 12p and next generation sequencing showed gains of 12p. Case 1, 2 and 4 showed metastatic disease on follow-up.ConclusionsDiagnosis of pure post-pubertal YST remains challenging due to the variety of morphologic patterns often present in these tumors. Extensive sampling along with use of ancillary tests is the key for diagnosis. In this study, 75 % of cases had metastatic disease at or after the diagnosis confirming the aggressive nature of this rare entity.     

Histologically confirmed intracranial germ cell tumors; an analysis of 62 patients in a single institute

This study was undertaken to document the clinicopathologic characteristics of histologically verified, primary intracranial germ cell tumors (GCTs), determine treatment outcomes, and to identify prognostic factors. The records of 62 patients (45 males and 17 females) with a primary intracranial GCT were retrospectively analyzed. Mean patient age was 18 years, and median follow-up was 41 months. The most common histological subtypes were germinoma (48.4%), followed by mixed GCT (27.4%), and teratoma (19.4%). In 23 patients (37.1%), disease onset occurred between 16 and 20 years. Germinomas and malignant non-germinomatous germ cell tumors were most prevalent in the pineal gland, suprasellar region, and basal ganglia, whereas teratomas dominated at other sites. Synchronous bifocal GCTs were found in six patients. Five-year overall survival (OS) rates according to a therapeutic classification proposed by Sawamura were 82.93%, 83.08%, and 64.71% in the good, intermediate, and poor prognosis groups, respectively (P = 0.2839). Five-year OSs in patients with normal tumor marker (αFP or βHCG) and patients with elevated marker were 85.26% and 66.96%, respectively (P = 0.0568). Five of six patients with alpha-fetoprotein (α-FP) of >1,000 ng/ml succumbed to disease, whereas all five patients with a beta-human chorionic gonadotropin of >1,000 mIU/ml survived. Mixed GCTs are more common in Korea than in the West. Sawamura’s classification of intracranial GCT may be a fine tool for stratifying patients’ survival. Patients with elevated tumor marker levels may appear to have poorer OS independent of histology. In particular, high titers of α-FP seem to impact prognosis.     

High-throughput microRNAome analysis in human germ cell tumours

Testicular germ cell tumours (GCTs) of adolescents and adults can be subdivided into seminomas (referred to as dysgerminomas of the ovary) and non-seminomas, all referred to as type II GCTs. They originate from carcinoma in situ (CIS), being the malignant counterparts of primordial germ cells (PGCs)/gonocytes. The invasive components mimic embryogenesis, including the stem cell component embryonal carcinoma (EC), the somatic lineage teratoma (TE), and the extra-embryonic tissues yolk sac tumour (YST) and choriocarcinoma (CH). The other type is the so-called spermatocytic seminomas (SS, type III GCT), composed of neoplastic primary spermatocytes. We reported previously that the miRNAs hsa-miR 371-373 cluster is involved in overruling cellular senescence induced by oncogenic stress, allowing cells to become malignant. Here we report the first high-throughput screen of 156 microRNAs in a series of type II and III GCTs (n = 69, in duplicate) using a quantitative PCR-based approach. After normalization to allow inter-sample analysis, the technical replicates clustered together, and the previous hsa-miRNA 371-373 cluster finding was confirmed. Unsupervised cluster analysis demonstrated that the cell lines are different from the in vivo samples. The in vivo samples, both normal and malignant, clustered predominantly based on their maturation status. This parallels normal embryogenesis, rather than chromosomal anomalies in the tumours. miRNAs within a single cluster showed a similar expression pattern, implying common regulatory mechanisms. Normal testicular tissue expressed most discriminating miRNAs at a higher level than SE and SS. Moreover, differentiated non-seminomas showed overexpression of discriminating miRNAs. These results support the model that miRNAs are involved in regulating differentiation of stem cells, retained in GCTs.     

The pluripotential nature of the mesenchyme-like component of yolk sac tumor

Germ cell neoplasms were reviewed for the investigation of a mesenchyme-like component of yolk sac tumor (YST) characterized by spindle cells with few mitoses in a myxoid, vascular background. Nineteen YSTs with this pattern were identified. The mesenchyme-like component of these YSTs appeared to derive from the epithelial elements of YST, since cytokeratin as well as vimentin positivity occurred in the spindle cells of the mesenchyme-like areas and foci of epithelial-spindle cell transition were present. In some cases the mesenchyme-like component showed differentiated mesenchymal elements (usually skeletal muscle). Similar features were identified in 13 chemotherapy-treated cases of YST that consisted only of this mesenchyme-like component. The mesenchyme-like component of YST appears to represent a chemoresistant, pluripotential cell population arising from metaplasia of YST epithelium; it may give rise to sarcomas occurring in some patients with treated germ cell tumors.     

Malignant germ cell tumors in men aged 50 years and over are associated with adverse pathologic features and higher stage at presentation

BackgroundGerm cell tumors (GCT) are the most common malignancy in men in the third and fourth decades of life. The occurrence of malignant GCT in men aged 50 years or over is rare, and their histopathologic characteristics and outcome is insufficiently characterized in the medical literature. Hence, we report the histopathologic features and clinical outcome of malignant GCTs in men aged ≥50 years at our institution.DesignWe performed a retrospective search of our database from 2005 to 2021 to identify men aged 50 years or older with malignant GCT. Cases of spermatocytic tumor were excluded. Clinical and histopathologic features of the tumors were reviewed.ResultsForty-seven cases were identified, showing a sharp decline in incidence over the age of 65. Thirty-nine (83 %) tumors were testicular while eight (17 %) were non-testicular in presentation. Cases included 26 (55 %) seminomas, 15 (32 %) non-seminoma/mixed malignant GCT, and 5 (11 %) regressed testicular germ cell tumors. The most common component in mixed malignant GCTs was embryonal carcinoma (77 %), followed by seminoma and yolk sac tumor (62 % each). Germ cell neoplasia in situ (GCNIS) accompanied 57 % of the cases. Aggressive pathologic features, including lymphovascular invasion, retroperitoneal/lymph node involvement and higher stage at presentation, were identified in a significant proportion of cases (36/47, 77 %). Clinical follow up showed six patients (14 %) died of disease-related causes.ConclusionOur findings expand and corroborate the previously reported data on malignant GCT in older men. Unique characteristics include tendency for higher stage at presentation with adverse pathologic features and more aggressive clinical course.