New insights from basic research on testicular germ cell tumors and updated tumorigenesis

The College of American Pathologists offers these protocols to assist pathologists in providing clinically useful and relevant information when reporting results of surgical specimen examinations. The College regards the reporting elements in the ‘‘Surgical Pathology Cancer Case Summary (Checklist)’’ portion of the protocols as essential elements of the pathology report. However, the manner in which these elements are reported is at the discretion of each specific pathologist, taking into account clinician preferences, institutional policies, and individual practice. The College developed these protocols as an educational tool to assist pathologists in the useful reporting of relevant information. It did not issue the protocols for use in litigation, reimbursement, or other contexts. Nevertheless, the College recognizes that the protocols might be used by hospitals, attorneys, payers, and others. Indeed, effective January 1, 2004, the Commission on Cancer of the American College of Surgeons mandated the use of the checklist elements of the protocols as part of its Cancer Program Standards for Approved Cancer Programs. Therefore, it becomes even more important for pathologists to familiarize themselves with these documents. At the same time, the College cautions that use of the protocols other than for their intended educational purpose may involve additional considerations that are beyond the scope of these documents.

ZBTB16: a novel sensitive and specific biomarker for yolk sac tumor

Testicular seminoma and non-seminoma: ESMO-EURACAN Clinical Practice Guideline for diagnosis, treatment and follow-up

Germ cell tumors of the gonads: a selective review emphasizing problems in differential diagnosis, newly appreciated, and controversial issues

Germ cell tumors of the gonads: a selective review emphasizing problems in differential diagnosis, newly appreciated, and controversial issues

Testicular germ cell tumors (TGCTs) are ever more affecting the young male population. Germ cell neoplasia in situ (GCNIS) is the origin of TGCTs, namely, seminomas (SE) and a heterogeneous group of nonseminomas (NS) comprising embryonal carcinoma, teratoma, yolk sac tumor, and choriocarcinoma. Response to the treatment and prognosis, especially of NS, depend on precise diagnosis with a necessity for discovery of new biomarkers. We aimed to perform comprehensive in silico analysis at the DNA, RNA, and protein levels of six prospective (HOXA9, MGMT, CFC1, PRSS21, RASSF1A, and MAGEC2) and six known TGCT biomarkers (OCT4, SOX17, SOX2, SALL4, NANOG, and KIT) and assess its congruence with histopathological analysis in all forms of TGCTs. Cancer Hallmarks Analytics Tool, the Search Tool for the Retrieval of Interacting Genes/Proteins database, and UALCAN, an interactive web resource for analyzing cancer OMICS data, were used. In 108 TGCT and 48 tumor-free testicular samples, the immunoreactivity score (IRS) was calculated. SE showed higher frequency in DNA alteration, while DNA methylation was significantly higher for all prospective biomarkers in NS. In GCNIS, we assessed the clinical positivity of RASSF1 and PRSS21 in 52% and 62% of samples, respectively, in contrast to low or nil positivity in healthy seminiferous tubules, TGTCs as a group, SE, NS, or all NS components. Although present in approximately 80% of healthy seminiferous tubules (HT) and GCNIS, HOXA9 was diagnostically positive in 64% of TGCTs, while it was positive in 82% of NS versus 29% of SE. Results at the DNA, mRNA, and protein levels on putative and already known biomarkers were included in the suggested panels that may prove to be important for better diagnostics of various forms of TGCTs.

Type II germ cell tumors arise after puberty from a germ cell that was incorrectly programmed during fetal life. Failure of testicular germ cells to properly differentiate can lead to the formation of germ cell neoplasia in situ of the testis; this precursor cell invariably gives rise to germ cell cancer after puberty. The Nodal co-receptor Cripto is expressed transiently during normal germ cell development and is ectopically expressed in non-seminomas that arise from germ cell neoplasia in situ, suggesting that its aberrant expression may underlie germ cell dysregulation and hence germ cell cancer. Here we investigated methylation of the Cripto promoter in mouse germ cells and human germ cell cancer and correlated this with the level of CRIPTO protein expression. We found hypomethylation of the CRIPTO promoter in undifferentiated fetal germ cells, embryonal carcinoma and seminomas, but hypermethylation in differentiated fetal germ cells and the differentiated types of non-seminomas. CRIPTO protein was strongly expressed in germ cell neoplasia in situ along with embryonal carcinoma, yolk sac tumor and seminomas. Further, cleaved CRIPTO was detected in media from seminoma and embryonal carcinoma cell lines, suggesting that cleaved CRIPTO may provide diagnostic indication of germ cell cancer. Accordingly, CRIPTO was detectable in serum from 6/15 patients with embryonal carcinoma, 5/15 patients with seminoma, 4/5 patients with germ cell neoplasia in situ cells only and in 1/15 control patients. These findings suggest that CRIPTO expression may be a useful serological marker for diagnostic and/or prognostic purposes during germ cell cancer management.

Germ cell tumors (GCTs) are the most common type of cancer in Germany in young men between 15 and 44years of age. The routinely performed diagnostic procedures are essential for the patient's treatment, but can be difficult due to heterogenous histologies. Additionally, the molecular mechanisms of the development of the special forms growing teratoma syndrome (GTS) and testicular tumors with malignant somatic transformation (MST) as well as of therapy resistance are not fully understood. Updated understanding of the molecular processes underlying GCT development and their special forms as well as recommendations for new and useful biomarkers. The development of GCTs is adynamic process largely influenced by the microenvironment. Seminomas (SEs) in particular seem to posses ahigher cellular plasticity than previously assumed, allowing SEs to be reprogrammed into an embryonal carcinoma (EC) or differentiate into extra-embryonal tissues (yolk sac tumors [YSTs], trophoblastic differentiation). Novel serological (mi371a-3p) and pathological (FOXA2) biomarkers are well suited to early detect GCTs and YSTs, respectively. For more aggressive tumors and special cases (GTS, MST), there are still no reliable diagnostics or specific/tailored therapies available. The ability of SEs to transit into EC or YSTs should be considered during therapy. Future research should focus on deciphering the special forms GTS and MST as well as the early recognition of YSTs, since their development seems to be an escape mechanism to chemotherapy.

Testicular germ cell tumors (TGCTs) share germline ancestry but diverge phenotypically and clinically as seminoma (SE) and nonseminoma (NSE), the latter including the pluripotent embryonal carcinoma (EC) and its differentiated derivatives, teratoma (TE), yolk sac tumor (YST), and choriocarcinoma. Epigenomes from TGCTs may illuminate reprogramming in both normal development and testicular tumorigenesis. Herein we investigate pure-histological forms of 130 TGCTs for conserved and subtype-specific DNA methylation, including analysis of relatedness to pluripotent stem cell (ESC, iPSC), primordial germ cell (PGC), and differentiated somatic references. Most generally, TGCTs conserve PGC-lineage erasure of maternal and paternal genomic imprints and DPPA3 (also known as STELLA); however, like ESCs, TGCTs show focal recurrent imprinted domain hypermethylation. In this setting of shared physiologic erasure, NSEs harbor a malignancy-associated hypermethylation core, akin to that of a diverse cancer compendium. Beyond these concordances, we found subtype epigenetic homology with pluripotent versus differentiated states. ECs demonstrate a striking convergence of both CpG and CpH (non-CpG) methylation with pluripotent states; the pluripotential methyl-CpH signature crosses species boundaries and is distinct from neuronal methyl-CpH. EC differentiation to TE and YST entails reprogramming toward the somatic state, with loss of methyl-CpH but de novo methylation of pluripotency loci such as NANOG. Extreme methyl-depletion among SE reflects the PGC methylation nadir. Adjacent to TGCTs, benign testis methylation profiles are determined by spermatogenetic proficiency measured by Johnsen score. In sum, TGCTs share collective entrapment in a PGC-like state of genomic-imprint and DPPA3 erasure, recurrent hypermethylation of cancer-associated targets, and subtype-dependent pluripotent, germline, or somatic methylation.

Testicular mixed germ cell tumors: a morphological and immunohistochemical study using stem cell markers, OCT3/4, SOX2 and GDF3, with emphasis on morphologically difficult-to-classify areas

Testicular tumors are incredibly diverse and one of the most challenging areas in surgical pathology. Because of the rarity and overlapping features with numerous entities occurring in the testis and paratestis, these tumors pose a diagnostic challenge even to the most experienced general pathologists. In 2016, the latest "World Health Organization (WHO) classification of testicular tumors" was released, which incorporated several updates to the previous 2004 classification system. These updates involved several entities, including germ cell tumors, sex cord-stromal tumors, tumors containing both germ cells and sex-cord stromal cells, a miscellaneous group of testicular tumors and paratesticular tumors. In addition, significant changes were also introduced in the 2018 AJCC TNM staging (8th edition) regarding testicular tumors. The germ cell tumors are divided into 2 major groups; tumors derived from germ cell neoplasia in situ (GCNIS) and those unrelated to GCNIS. The GCNIS associated tumors include seminomatous and nonseminomatous germ cell tumors, which constitute a heterogeneous group of tumors. Non-GCNIS-associated tumors include prepubertal-type teratoma, prepubertal yolk sac tumor, mixed prepubertal-type teratoma and yolk sac tumor and spermatocytic seminoma. In the sex cord-stromal category, the tumors are classified based on their cells of origin. Most are Leydig cell tumors and Sertoli cell tumors; however, several mixed and diverse entities based on cell types are included in this group. Gonadoblastoma is the only tumor in the mixed germ cell and sex cord-stromal tumor category. Because of recent advances in molecular techniques, abundant new genetic information has emerged which helped classify the tumors based on the molecular alterations and provided insights into the tumor pathogenesis. This review focused on the updates related to testicular germ cell tumors and sex cord-stromal tumors and described the morphologic, immunohistochemical and molecular characteristics with an aim to provide a practical diagnostic approach and an update on relevant recent molecular advances.

A Big Catch for Germ Cell Tumour Research

We evaluated p53 expression and tumor proliferative activity (TPA) using monoclonal antibodies to Ki-67 and proliferating cell nuclear antigen (PCNA) in 26 patients with seminomatous and nonseminomatous testicular germ-cell tumors (GCTs). Correlation between p53 expression and TPA, as well as the clinical correlation with the expression of these proteins were also assessed. There were eight cases of pure seminoma and 18 cases of nonseminomatous GCTs, collectively consisting of 45 tumors or tumor components. The nonseminomatous GCTs were mixed or pure and included choriocarcinoma (CC), embryonal carcinoma (EC), immature teratoma (IMT), mature teratoma (MT), seminoma, and yolk sac tumor (YST). The ages of the patients with seminomatous GCTs ranged from 24 to 47 years (mean, 34 years) and those for patients with nonseminomatous GCTs ranged from 17 to 43 years (mean, 29 years). Sixteen (44%) of the 36 nonseminomatous GCTs or tumor components were positive for p53 protein. Ten (91%) of eleven ECs, three (38%) of eight YSTs, two (20%) of ten MTs, and the single case of CC were positive for p53 protein. All nine seminomas and three of six IMTs were only focally positive for p53 protein. The p53 expression in ECs and YSTs was significantly higher than that in IMTs, MTs, and seminomas (P=0.0001). TPA was present in the majority of the seminomatous and nonseminomatous GCTs, and was significantly higher in ECs and YSTs than in seminomas, MTs, and IMTs (Ki-67, P=0.0001; PCNA, P=0.0006). In the majority of the cases PCNA expression was higher than Ki-67 expression (P=0.0001). The mean TPA percentage was significantly higher in the p53-positive tumors or tumor components (EC and YST) when compared with the mean TPA percentage in those neoplasms that were focally positive or negative for p53 protein (Ki-67, P=0.003; PCNA, P=0.046). p53 expression was also associated with histologically aggressive tumors (ECs and YSTs) that also exhibit high TPA. No relationship appears to exist between the three tumor markers and the clinical stage or the patients' follow-up and outcome in this small series. Further studies are necessary to elucidate the roles of p53 and proliferation markers in testicular tumorigenesis and as prognostic markers.

Therapeutic Potential of SOX2 Inhibition for Embryonal Carcinoma

The classic testicular tumor marker alpha-fetoprotein (AFP) is associated with nonseminomatous germ cell tumors, including embryonal carcinoma, yolk sac tumor, and teratoma. AFP is not considered to be produced by pure seminoma. However, postmortem studies have demonstrated that 30 to 45% of patients who died of seminoma initially diagnosed harbored nonseminomatous metastases and had an elevated serum AFP. We analyzed AFP expression by immunohistochemistry and by nested reverse transcription-polymerase chain reaction (RT-PCR) in 10 seminomas, 3 embryonal carcinomas, and 1 immature teratoma, diagnosed by traditional clinical methods. Positive immunohistochemical staining was observed in all embryonal carcinomas and in the teratoma but not in the seminomas. AFP mRNA, however, was found in 6 of 10 seminomas, in all embryonal carcinomas, and in the teratoma. The nucleotide sequence of PCR products was identical with that of the AFP gene. We conclude that the analysis of AFP gene expression by nested RT-PCR would be useful for detecting minute quantities of nonseminomatous germ cell elements in classic seminoma. Moreover, the existence of AFP mRNA suggests the possibility that seminoma cells can differentiate into nonseminomatous germ cells.