Pathogenesis and pathobiology of testicular germ cell tumours: a view from a developmental biological perspective with guidelines for pathological diagnostics.

Testicular germ cell tumours (GCT) are divided into three different subtypes (types I-III) regarding to their developmental origin, histological differences and molecular features. Type I GCT develop from disturbed primordial germ cells and most commonly occur in children and young adolescents, which is why they are referred to as prepubertal GCT. Type II GCT develop from a non-invasive germ cell neoplasia in situ (GCNIS) and show an isochromosome 12p (i12p) or gain of 12p material as a common and characteristic molecular alteration. Type III GCT originate from distorted postpubertal germ cells (e.g. spermatogonia) in adult patients and have changes on chromosome 9 with amplification of the DMRT1 gene. Type I GCT encompass prepubertal-type teratomas and yolk-sac tumours (YST). Type II GCT include seminoma, embryonal carcinoma, choriocarcinoma, postpubertal-type teratoma and postpubertal-type YST. Types I and II GCT both show similar morphology, but are separated from each other by the detection of a GCNIS and an i12p in type II GCT. For type II GCT it is especially important to detect non-seminomatous elements, as these tumours have a worse biological behaviour and need a different treatment to seminomas. In contrast to types I and II GCT, type III tumours are equivalent to spermatocytic tumours and usually occur in elderly men, with few exceptions in young adults. The development of types I and II GCT seems to depend not upon driver mutations, but rather on changes in the epigenetic landscape. Furthermore, different pluripotency associated factors (e.g. OCT3/4, SOX2, SOX17) play a crucial role in GCT development and can be used as immunohistochemical markers allowing to distinguish the different subtypes from each other in morphologically challenging tissue specimens. Especially in metastatic sites, a morphological and immunohistochemical diagnostic algorithm is important to detect small subpopulations of each non-seminomatous GCT subtype, which are associated with a poorer prognosis and need a different treatment. Furthermore, primary extragonadal GCT of the retroperitoneum or mediastinum develop from misguided germ cells during embryonic development, and might be challenging to detect in small tissue biopsies due to their rarity at corresponding sites. This review article summarises the pathobiological and developmental aspects of the three different types of testicular GCT that can be helpful in the histopathological examination of tumour specimens by pathologists.

[Fundamentals in the pathology of testicular tumours]. / Grundlagen der Pathologie seltener Hodentumoren.

The most common group of testicular tumours comprises germ cell tumours. Other primary testicular tumours are rare, but it is important to be aware of the wide variety of other, much rarer testicular tumours for the differential diagnosis. These tumours include sex cord stromal tumours and testicular adnexal tumours, which must be distinguished from metastases or somatic-type malignancies in germ cell tumours. Immunohistochemical markers and molecular alterations can help to correctly diagnose these tumours.

Genetic landscape of pediatric acute liver failure of indeterminate origin.

BACKGROUND AND AIMS: Pediatric acute liver failure (PALF) is a life-threatening condition. In Europe, the main causes are viral infections (12%-16%) and inherited metabolic diseases (14%-28%). Yet, in up to 50% of cases the underlying etiology remains elusive, challenging clinical management, including liver transplantation. We systematically studied indeterminate PALF cases referred for genetic evaluation by whole-exome sequencing (WES), and analyzed phenotypic and biochemical markers, and the diagnostic yield of WES in this condition. APPROACH AND RESULTS: With this international, multicenter observational study, patients (0-18 y) with indeterminate PALF were analyzed by WES. Data on the clinical and biochemical phenotype were retrieved and systematically analyzed. RESULTS: In total, 260 indeterminate PALF patients from 19 countries were recruited between 2011 and 2022, of whom 59 had recurrent PALF. WES established a genetic diagnosis in 37% of cases (97/260). Diagnostic yield was highest in children with PALF in the first year of life (41%), and in children with recurrent acute liver failure (64%). Thirty-six distinct disease genes were identified. Defects in NBAS (n=20), MPV17 (n=8), and DGUOK (n=7) were the most frequent findings. When categorizing, the most frequent were mitochondrial diseases (45%), disorders of vesicular trafficking (28%), and cytosolic aminoacyl-tRNA synthetase deficiencies (10%). One-third of patients had a fatal outcome. Fifty-six patients received liver transplantation. CONCLUSIONS: This study elucidates a large contribution of genetic causes in PALF of indeterminate origin with an increasing spectrum of disease entities. The high proportion of diagnosed cases and potential treatment implications argue for exome or in future rapid genome sequencing in PALF diagnostics.

Primary germ cell tumours of the mediastinum: A review with emphasis on diagnostic challenges.

This article will review current aspects of the histopathological, immunohistochemical and molecular analysis of primary mediastinal germ cell tumours (PMGCTs) as well as their aetiological, epidemiological, clinical and therapeutic features. PMGCTs represent an important differential diagnosis in the spectrum of mediastinal tumours, and their diagnosis is usually made on small tissue samples from core needle biopsies in combination with diagnostic imaging and serum tumour markers. As in lymphomas, a small biopsy is often the only viable tumour sample available from these patients, as they receive chemotherapy prior to eventual surgical resection. Pathologists therefore need to apply an efficient combination of immunohistochemical markers to confirm the diagnosis of a PMGCT and to exclude morphological mimics.

[Fundamentals in the pathology of testicular germ cell tumours]. / Grundlagen der Pathologie von Keimzelltumoren des Hodens.

Testicular germ cell tumours (GCT) represent the most common malignant neoplasia in young male adults between the age of 15 and 44. Because of their different biological behaviour it is important to differentiate prepubertal GCTs from postpubertal GCTs. This distinction is made by presence or absence of a germ cell neoplasia in situ. Histopathological diagnostics can be challenging due to different tumour subtypes and their different growth patterns. Therefore, knowledge of morphologic variants and immunohistochemical markers is important.

Metallothionein: a game changer in histopathological diagnosis of Wilson disease.

AIMS: Wilson disease (WD) is a genetic disorder of copper metabolism caused by mutations in the ATP7B gene. Toxic copper accumulation leads to hepatic, neurologic, and psychiatric disorders with variable presentation. Metallothionein (MT) immunohistochemistry was proposed as a diagnostic marker. METHODS: MT immunohistochemistry was performed on liver specimens of WD patients (n = 64) and control cases (n = 160) including acute liver failure, steatotic liver disease, autoimmune hepatitis, normal liver, primary biliary cholangitis, primary and secondary sclerosing cholangitis, and progressive familial intrahepatic cholestasis. The optimal cutoff for detection of WD was determined by receiver operating characteristic (ROC) analysis. RESULTS: At least moderate staining in >50% of hepatocytes was observed in 81% of analysed liver specimens (n = 56/69) of WD patients, while only five control cases showed this staining pattern. The sensitivity, specificity, and accuracy for a new diagnosis of WD were 85.7%, 96.9%, and 94.9%, respectively. Sensitivity in nonfibrotic patients was 70.6% and this MT pattern was robust in small biopsies. The hepatic copper concentration was similar between MT-positive and MT-negative liver samples (P > 0.05). Zinc treatment may induce hepatocellular MT expression. Kayser-Fleischer rings (50% versus 15%) and neurologic disorders (50% versus 13%) were significantly more prevalent in MT-negative compared to MT-positive WD patients, respectively. CONCLUSION: MT immunostaining is an excellent biomarker for histological diagnosis of WD, should be incorporated in the diagnostic work-up of patients with potential WD, and is useful in a modified Leipzig score.

Validation of a prediction system for risk of kidney allograft failure in pediatric kidney transplant recipients: An international observational study.

Predicting long-term kidney allograft failure is an unmet need for clinical care and clinical trial optimization in children. We aimed to validate a kidney allograft failure risk prediction system in a large international cohort of pediatric kidney transplant recipients. Patients from 20 centers in Europe and the United States, transplanted between 2004 and 2017, were included. Allograft assessment included estimated glomerular filtration rate, urine protein-to-creatinine ratio, circulating antihuman leukocyte antigen donor-specific antibody, and kidney allograft histology. Individual predictions of allograft failure were calculated using the integrative box (iBox) system. Prediction performances were assessed using discrimination and calibration. The allograft evaluations were performed in 706 kidney transplant recipients at a median time of 9.1 (interquartile range, 3.3-19.2) months posttransplant; mean estimated glomerular filtration rate was 68.7 ± 28.1 mL/min/1.73 m2, and median urine protein-to-creatinine ratio was 0.1 (0.0-0.4) g/g, and 134 (19.0%) patients had antihuman leukocyte antigen donor-specific antibodies. The iBox exhibited accurate calibration and discrimination for predicting the outcomes up to 10 years after evaluation, with a C-index of 0.81 (95% confidence interval, 0.75-0.87). This study confirms the generalizability of the iBox to predict long-term kidney allograft failure in children, with performances similar to those reported in adults. These results support the use of the iBox to improve patient monitoring and facilitate clinical trials in children.

The Subtype Identity of Testicular Cancer Cells Determines Their Immunostimulatory Activity in a Coculture Model.

Testicular germ cell cancer (TGCC) is subdivided into several subtypes. While seminomatous germ cell tumors (SGCT) are characterized by an intensive infiltration of immune cells which constitute a pro-inflammatory tumor micromilieu (TME), immune cells in non-seminomatous germ cell tumors (NSGCT) are differently composed and less abundant. Previously, we have shown that the seminomatous cell line TCam-2 promotes T cell and monocyte activation in a coculture model, resulting in mutual interactions between both cell types. Here we set out to compare this feature of TCam-2 cells with the non-seminomatous cell line NTERA-2. Peripheral blood T cells or monocytes cocultured with NTERA-2 cells failed to secrete relevant amounts of pro-inflammatory cytokines, and significantly downregulated the expression of genes encoding activation markers and effector molecules. In contrast, immune cells cocultured with TCam-2 cells produced IL-2, IL-6 and TNFα, and strongly upregulated the expression of multiple pro-inflammatory genes. Furthermore, the expression of genes involved in proliferation, stemness and subtype specification remained unaltered in NTERA-2 cells during coculture with T cells or monocytes, indicating the absence of mutual interactions. Collectively, our findings uncover fundamental differences between SGCT and NSGCT in their capability to generate a pro-inflammatory TME, which possibly impacts the clinical features and prognosis of both TGCC subtypes.

Molecular HLA mismatching for prediction of primary humoral alloimmunity and graft function deterioration in paediatric kidney transplantation.

Introduction: Rejection remains the main cause of allograft failure in paediatric kidney transplantation and is driven by donor-recipient HLA mismatching. Modern computational algorithms enable assessment of HLA mismatch immunogenicity at the molecular level (molecular-mismatch, molMM). Whilst molMM has been shown to correlate with alloimmune outcomes, evidence demonstrating improved prediction performance against traditional antigen mismatching (antMM) is lacking. Methods: We analysed 177 patients from the CERTAIN registry (median follow-up 4.5 years). molMM scores included Amino-Acid-Mismatch-Score (AAMS), Electrostatic-Mismatch-Score (EMS3D) and netMHCIIpan (netMHC1k: peptide binding affinity ≤1000 nM; netMHC: binding affinity ≤500 nM plus rank <2%). We stratified patients into high/low-risk groups based on risk models of DSA development. Results: Donor-specific HLA antibodies (DSA) predominantly targeted the highest scoring molMM donor antigen within each HLA locus. MolMM scores offered superior discrimination versus antMM in predicting de novo DSA for all HLA loci; the EMS3D algorithm had particularly consistent performance (area under the receiver operating characteristic curve (AUC) >0.7 for all HLA loci vs. 0.52-0.70 for antMM). ABMR (but not TCMR) was associated with HLA-DQ molMM scores (AAMS, EMS3D and netMHC). Patients with high-risk HLA-DQ molMM had increased risk of graft function deterioration (50% reduction in baseline eGFR (eGFR50), adjusted HR: 3.5, 95% CI 1.6-8.2 high vs. low EMS3D). Multivariable modelling of the eGFR50 outcome using EMS3D HLA-DQ stratification showed better discrimination (AUC EMS3D vs. antMM at 2 years: 0.81 vs. 0.77, at 4.5 years: 0.72 vs. 0.64) and stratified more patients into the low-risk group, compared to traditional antMM. Conclusion: Molecular mismatching was superior to antigen mismatching in predicting humoral alloimmunity. Molecular HLA-DQ mismatching appears to be a significant prognostic factor for graft function deterioration in paediatric kidney transplantation.

Corrigendum: Molecular HLA mismatching for prediction of primary humoral alloimmunity and graft function deterioration in paediatric kidney transplantation.

[This corrects the article DOI: 10.3389/fimmu.2023.1092335.].

Etiology and Outcome of Adult and Pediatric Acute Liver Failure in Europe.

Acute liver failure (ALF) is rare but life-threatening. Common causes include intoxications, infections, and metabolic disorders. Indeterminate etiology is still frequent. No systematic data on incidence, causes, and outcome of ALF across Europe are available. Via an online survey we reached out to European Reference Network Centers on rare liver diseases. Numbers and etiology of ALF cases during 2020 were retrieved and diagnostic and treatment availabilities assessed. In total, 455 cases (306 adult, 149 pediatric) were reported from 36 centers from 20 countries. Intoxication was the most common cause in adult and pediatric care. The number of cases with indeterminate etiology is low. Diagnostic tools and specific treatment options are broadly available within this network. This is the first approach to report on etiology and outcome of ALF in the pediatric and adult population in Europe. High diagnostic yield and standard of care reflects the expert status of involved centers.

Missing trial results: analysis of the current publication rate of studies in pediatric dialysis from 2003 to 2020.

BACKGROUND: Decision-making in the field of pediatric dialysis requires evidence from clinical trials, but, similar to other fields of pediatric medicine, might be affected by a low trial publication rate. METHODS: We analyzed the current publication rate, the time to publication, and factors that might be associated with both rate of and time to publication in pediatric dialysis studies registered as completed on ClinicalTrials.gov from 2003 until November 2020. RESULTS: Fifty-three respective studies were identified. These enrolled 7287 patients in total. 28 of 53 studies (52.8%) had results available. We identified a median time to publication of 20.5 months (range, 3-67). Studies published after the FDA Amendments Act establishment in 2007 were published faster (P = 0.025). There was no trend toward a higher publication rate of studies completed more recently (P = 0.431). 26 of 53 studies (49.1%) focused on medication and control of secondary complications of kidney failure. 12 of 53 studies (22.6%) enrolled only children, were published faster (P = 0.029) and had a higher 5-year publication rate (P = 0.038) than studies enrolling both children and adults. 25 of 53 studies (47.1%) were co-funded by industry. These were published faster (P = 0.025). CONCLUSIONS: Currently, only 52.8% of all investigated studies in pediatric dialysis have available results, and the overall median time to publication did not meet FDA requirements. This might introduce a publication bias into the field, and it might negatively impact clinical decision-making in this critical subspecialty of pediatric medicine. A higher resolution version of the Graphical abstract is available as Supplementary information.

Emulation of the control cohort of a randomized controlled trial in pediatric kidney transplantation with Real-World Data from the CERTAIN Registry.

BACKGROUND: Randomized controlled trials in pediatric kidney transplantation are hampered by low incidence and prevalence of kidney failure in children. Real-World Data from patient registries could facilitate the conduct of clinical trials by substituting a control cohort. However, the emulation of a control cohort by registry data in pediatric kidney transplantation has not been investigated so far. METHODS: In this multicenter comparative analysis, we emulated the control cohort (n = 54) of an RCT in pediatric kidney transplant patients (CRADLE trial; ClinicalTrials.gov NCT01544491) with data derived from the Cooperative European Paediatric Renal Transplant Initiative (CERTAIN) registry, using the same inclusion and exclusion criteria (CERTAIN cohort, n = 554). RESULTS: Most baseline patient and transplant characteristics were well comparable between both cohorts. At year 1 posttransplant, a composite efficacy failure end point comprising biopsy-proven acute rejection, graft loss or death (5.8% ± 3.3% vs. 7.5% ± 1.1%, P = 0.33), and kidney function (72.5 ± 24.9 vs. 77.3 ± 24.2 mL/min/1.73 m2 P = 0.19) did not differ significantly between CRADLE and CERTAIN. Furthermore, the incidence and severity of BPAR (5.6% vs. 7.8%), the degree of proteinuria (20.2 ± 13.9 vs. 30.6 ± 58.4 g/mol, P = 0.15), and the key safety parameters such as occurrence of urinary tract infections (24.1% vs. 15.5%, P = 0.10) were well comparable. CONCLUSIONS: In conclusion, usage of Real-World Data from patient registries such as CERTAIN to emulate the control cohort of an RCT is feasible and could facilitate the conduct of clinical trials in pediatric kidney transplantation. A higher resolution version of the Graphical abstract is available as Supplementary information.

Generating evidence for diagnosis and therapy of RarE LIVEr disease: the RELIVE Initiative for systematic reviews and meta-analyses.

BACKGROUND: Rare liver lesions and diseases have seldomly aroused major interest of researchers. For most guidelines, presumably similar clinical conditions are pooled without detailed investigations of singularities that they present. MAIN TEXT: A multidisciplinary project aiming to establish evidence-based therapies for rare liver diseases has been founded. A series of systematic reviews and meta-analyses will be the starting point for a structured development of guidelines for rare conditions of the liver affecting pediatric and adult populations. The novel approach will be focusing on case reports and small patient series with distinct rare liver diseases without pooling several presumably acceptably similar conditions. Thus, a vital resource of information will be utilized, which has been largely neglected hitherto. CONCLUSION: Highly specific recommendations based on highest available evidence will therefore be developed for specific conditions, advancing the individualized medicine approach for the afflicted patients.

[Diagnostic problems in testicular tumours in consultant pathology : A practical guide]. / Diagnostische Probleme bei Hodentumoren in der Konsiliarpathologie : Ein praktischer Leitfaden.

The great variety of pathological patterns in germ cell tumours, especially in yolk sac tumours but also the possibility of somatic-type malignancies, can complicate daily diagnosis. For the correct diagnosis, knowledge of morphological aspects and additional immunohistochemical staining can be helpful. Also, rare entities like sex cord stromal tumours, tumours of testicular adnexa or mesenchymal tumours of the spermatic cord can be diagnostically challenging.

[New 2022 WHO classification of testicular tumours]. / Neue WHO-Klassifikation der Hodentumoren 2022.

The 5th edition of the WHO Classification of Tumours: Urinary and Male Genital Tumours includes some important revisions of the testicular tumour classifications, which are summarized in this article. They concern, for example, the definition of tumours of neuroectodermal and neuroendocrine origin. Furthermore, signet-ring stromal tumours and myoid gonadal stromal tumours are listed as separate entities in the section about sex-cord stromal tumours. Moreover, lymphatic neoplasia as well as soft tissue tumours of the urinary and male genital tract are each combined in a common section.

Timing of reconstruction of the lower urinary tract in pediatric kidney transplant recipients: A CERTAIN multicenter analysis of current practice.

BACKGROUND: Preexistent LUTD are considered a hostile environment, which might negatively impact KTx survival. In such cases, surgical reconstruction of the bladder is required. However, there is still disagreement on the optimal timing of the reconstruction procedure. METHODS: This is a multicenter analysis of data from the CERTAIN Registry. Included were 62 children aged 8.18 ± 4.90 years, with LUTD. Study endpoints were the duration of initial posttransplant hospitalization, febrile UTIs, and a composite failure endpoint comprising decline of eGFR, graft loss, or death up to 5 years posttransplant. Outcome was compared to matched controls without bladder dysfunction. RESULTS: Forty-one patients (66.1%) underwent pretransplant and 14 patients (22.6%) posttransplant reconstruction. Bladder augmentation was performed more frequently in the pretransplant (61%) than in the posttransplant group (21%, p = .013). Outcome in the pre- and posttransplant groups and in the subgroups of patients on pretransplant PD with major bladder surgery either pre- (n = 14) or posttransplant (n = 7) was comparable. Outcomes of the main study cohort and the matched control cohort (n = 119) were comparable during the first 4 years posttransplant; at year 5, there were more events of transplant dysfunction in the study cohort with LUTD than in controls (p = .03). CONCLUSIONS: This multicenter analysis of the current practice of LUTD reconstruction in pediatric KTx recipients shows that pre- or posttransplant surgical reconstruction of the lower urinary tract is associated with a comparable 5-year outcome.

Publication rate and research topics of studies in pediatric kidney transplantation.

BACKGROUND: The quality of medical care for pediatric kidney transplant recipients depends on sound evidence from published clinical trials. METHODS: We examined the publication rate, time to publication, and factors associated with publication of studies in pediatric kidney transplantation registered on ClinicalTrials.gov from 1999 to 2020. RESULTS: We identified 136 studies with an overall enrollment of 36255 study participants, of which only 58.8% have been published yet. Unpublished studies included data from 14 350 participants. The median time to publication was 25 months (range, 0-117) with a significantly shorter time to publication in more recent years. The most frequently investigated research topic was immunosuppressants (49.3%), followed by perioperative management (11.0%) and infectiology (10.3%). The percentage of published studies was highest for the topic steroid withdrawal (87.5%), followed by infectiology (78.6%), and nutrition, sports and quality of life (71.4%). Studies, which were co-funded by industry, showed a significantly higher 5-year publication rate (p = 0.019). CONCLUSIONS: In conclusion, nearly half of all studies in pediatric kidney transplantation remain unpublished. Non-publication of studies might lead to a publication bias with a negative impact on clinical decision-making.

A Coculture Model Mimicking the Tumor Microenvironment Unveils Mutual Interactions between Immune Cell Subtypes and the Human Seminoma Cell Line TCam-2.

Testicular germ cell cancer (TGCC) is the most common type of cancer in young men. Seminomas account for around half of them and are characterized by a pronounced infiltration of immune cells. So far, the impact of the tumor microenvironment (TME) on disease progression, especially the interaction of individual immune cell subtypes with the tumor cells, remains unclear. To address this question, we used an in vitro TME model involving the seminoma-derived cell line Tcam-2 and immune cell subsets purified from human peripheral blood. T cells and monocytes were strongly activated when individually cocultured with Tcam-2 cells as revealed by increased expression of activation markers and pro-inflammatory cytokines both on the mRNA and protein level. Importantly, the interaction between tumor and immune cells was mutual. Gene expression of pluripotency markers as well as markers of proliferation and cell cycle activity were upregulated in Tcam-2 cells in cocultures with T cells, whereas gene expression of SOX17, a marker for seminomas, was unaltered. Interestingly, the impact of monocytes on gene expression of Tcam-2 cells was less pronounced, indicating that the effects of individual immune cell subsets on tumor cells in the TME are highly specific. Collectively, our data indicate that seminoma cells induce immune cell activation and thereby generate a strong pro-inflammatory milieu, whereas T cells conversely increase the proliferation, metastatic potential, and stemness of tumor cells. Although the employed model does not fully mimic the physiological situation found in TGCC in vivo, it provides new insights potentially explaining the connection between inflammatory infiltrates in seminomas and their tendency to burn out and metastasize.