Mediastinal Germ Cell Tumors: A Review and Update on Pathologic, Clinical, and Molecular Features

Pediatric primary extragonadal choriocarcinoma - A study on male patients at a single tertiary medical institution

BACKGROUND

Primary extragonadal choriocarcinoma (PEGCC) in male is rare. It is highly malignant, typically presents with distant metastasis at the time of diagnosis, and responds poorly to treatment. Because of its associated high levels of PD-L1, the PD-1/PD-L1 pathway is a likely therapeutic target. Herein, we report our experience of treating pediatric PEGCC in six boys at a tertiary hospital.

METHODS

We analyzed the data of six boys with pathologically confirmed PEGCC between 2009 and 2021. Their clinicodemographic and histopathological characteristics as well as treatments and clinical outcomes were retrieved from their medical charts.

RESULTS

The patients' median age was 15 (range: 12-17) years. The most common primary tumor site was the mediastinum (67%, 4/6), with one case each in the retroperitoneum (16.7%) and brain (16.7%). Except for the patient with brain PEGCC, all presented with metastasis at the time of diagnosis. The following metastatic sites were observed: the lungs (100%, 5/5), brain (3/5, 60%), liver (3/5, 60%), kidneys (2/5, 40%), and spleen (1/5, 20%). Most patients had dry cough, dyspnea, and hemoptysis at initial presentation, likely due to lung metastasis. Serum human chorionic gonadotropin (HCG) levels were highly elevated in all patients. All patients received platinum-based cytotoxic chemotherapy. The patient with brain choriocarcinoma underwent surgical tumor resection; all others underwent only surgical biopsy. Strong positive PD-L1 immunohistochemical staining was noted for two patients. One patient received the PD-L1 inhibitor pembrolizumab and achieved a good response. Our cohort's 1-year survival rate was 33.3%, with a median survival of 4.34 months. Serum HCG levels remained normal in the two survivors during follow-up visits.

CONCLUSION

The poor response to current platinum-based chemotherapy remains a major challenge in the management of pediatric PEGCC. Adding pembrolizumab to a conventional chemotherapy regimen may improve the outcomes in boys with PEGCC.

Intrapericardial Teratoma and Associated 3q29 Deletion in a Fetus: Case Report

Depending on its location, size, and proximity to the cardiac structures, an intrapericardial teratoma may lead to severe circulatory disturbances and even fetal demise. A 34-year-old G2P1 presented at 20w5d with a solid cystic mass in the right thorax of the fetus, originating from the right atrium or lung, with signs of non-immune fetal hydrops, soon resulting in intrauterine fetal death. Detailed post-mortem autopsy revealed signs of hydrops fetalis universalis due to a spherical tumor mass originating from the aortic root. Histologic examination of the tumor showed the characteristic morphology of a teratoma. A 1.6-Mb microdeletion at 3q29 was identified by single nucleotide polymorphism array. This is the first report presenting the diagnosis of an intrapericardial teratoma in a fetus with a microdeletion of 3q29. Intrapericardial teratoma has a poor prognosis and the fetal outcome relies on the development of hydrops. A post-mortem examination is essential in order to make a definitive diagnosis, which underlines the status of the fetal pathologist and the need for interdisciplinary cooperation.

Primary mediastinal seminoma with azoospermia: case report and review of the literature

Introduction

Since the first report, primary mediastinal seminoma has a low incidence in the population, and it mainly affects young and middle-aged men, is clinically rare, and accounts for a very small proportion of mediastinal tumors. In this study, we describe the first case of primary mediastinal seminoma with azoospermia and hypothesize that the coexistence of the two disorders may not be a coincidence.

Case report

A 16-year-old man presented with chest tightness and chest pain, a mediastinal mass on chest CT, and abnormal 18F-fluoro-deoxyglucose uptake on a PET-CT scan. By biopsy of the mass, the pathological diagnosis was a primary mediastinal seminoma. Because chemotherapy is included in the treatment of the tumor, the patient underwent sperm freezing before treatment, considering that chemotherapy can affect fertility, but the patient was diagnosed with azoospermia. Finally, the patient underwent tumor resection and postoperative chemotherapy. No tumor recurrence was observed at the current follow-up.

Conclusion

Primary mediastinal seminoma is mainly confirmed by histopathological examination, and surgery and chemoradiotherapy are the current treatments. In patients with mediastinal seminoma or azoospermia, doctors should be aware that the two disorders may coexist, especially in men who have fertility requirements or long-term infertility, and that examination of the mediastinum and semen may lead to unexpected findings in the diagnosis and treatment. For mediastinal germ cell tumors, genetic testing is of great value in the treatment of tumors and the prediction of associated diseases. Future studies exploring the potential correlation between mediastinal seminoma and azoospermia will be prospective.

Survival difference among adult and pediatric mediastinal yolk sac tumors cases: A meta-analysis of case reports

BACKGROUND

Mediastinal Yolk sac tumors (YST) are rare and highly malignant extragonadal germ cell tumors with rapid growth and early metastases. We sought to conduct a meta-analysis of published case reports/case series to compare differences in survival, demographics, and treatment modalities between adult and pediatric patients with YST.

METHODS

Ovid Embase, Cochrane, and Ovid Medline databases were searched for primary mediastinal pure YST cases. The primary outcome was overall survival (OS). Log-rank and Cox regression were used. This study is registered on PROSPERO (CRD42022367586).

RESULTS

Among 846 studies, 87 met our inclusion criteria including 130 patients (Adults: 90 and Pediatrics: 40). About 41.5% of the patients were from the United States. The median age was 23.0 (Q1-Q3: 17.0-30.0), 88.5% were males, and (32.3%) were Asian. Stage II represented almost 40%. AFP was elevated in 96.9%. Respiratory distress was the presenting symptom in 65.4%. Chemotherapy, radiotherapy, and surgery were utilized in 84.6, 23.1, and 64.7% respectively. Median OS was 24 months (Adults: 23 months, Pediatrics: 25 months, P = 0.89). 3- and 5-year OS were 34.4% and 22.9% in adults and 41.5% and 41.5% in pediatrics, respectively. On multivariate analysis, anterior location of tumors, receipt of chemotherapy, and undergoing surgery were associated with better OS.

CONCLUSION

Primary mediastinal YSTs are rare, but lethal neoplasms. Our meta-analysis showed that mediastinal YSTs mimic other non-seminomatous mediastinal GCTs in terms of clinical characteristics and available treatment options. Early diagnosis, neoadjuvant chemotherapy, and surgical resection are the key points for effective management and improved outcomes.

Review of clinical and diagnostic imaging of the thymus: from age-related changes to thymic tumors and everything in between

The thymus, a primary lymphoid organ of the immune system, undergoes several changes due to a variety of reasons, ranging from aging to pathological conditions. These changes can make distinguishing between benign and neoplastic changes in the thymus challenging, thereby complicating the histopathological diagnoses of thymic tumors. Moreover, most patients with thymic tumors are asymptomatic at the time of diagnosis. Therefore, imaging plays an extremely important role in the evaluation of thymic lesions. In this review, we introduced the imaging characteristics of the thymus, ranging from benign findings, such as normal maturation and benign lesions, to neoplasms.

Benign lesions of the mediastinum

Mediastinal tumours represent a heterogeneous group of entities derived from the manifold structures located in or adjacent to the mediastinum. Due to the occurrence of some of these tumours in characteristic mediastinal compartments, an anatomical subdivision of the mediastinum in the prevascular (anterior), visceral (middle), and paravertebral (posterior) is helpful for the differential diagnosis. Benign anterior mediastinal tumours linked to an enlargement of the thymic gland mainly consist of thymic cysts and several types of thymic hyperplasia: true thymic hyperplasia, rebound hyperplasia, lymphofollicular hyperplasia, and so-called thymic hyperplasia with lymphoepithelial sialadenitis (LESA)-like features. Mature teratomas, ectopic (para)thyroid tissue, and benign thymic tumours such as thymolipoma or thymofibrolipoma represent further typical tumours of the anterior mediastinum. Pericardial, bronchogenic, or oesophageal duplication cysts predominate in the middle mediastinum, whereas neurogenic tumours and myelolipomas are characteristic findings in the posterior compartment. Vascular tumours, lipomas, adenomatoid tumours, Castleman disease, or mediastinitis are further examples of less frequent tumours or tumorous lesions affecting the mediastinum. This review focuses on benign mediastinal lesions with an emphasis on benign tumours of the thymus. Besides histology, characteristic epidemiological and clinical aspects prerequisite for the correct diagnosis and patient management are discussed.

Cytopathologic diagnosis of extragonadal germ cell tumors: A 10-year institutional review

BACKGROUND

The occurrence of extragonadal germ cell tumors (EGGCTs), either as primary tumors or metastatic disease, is rare. Forms of cytologic sampling, including fluid analysis, fine-needle aspiration, and/or small-core needle biopsy, have been shown to be reliable methods for the diagnosis of germ cell tumors. This study aims to investigate the utility of cytopathologic techniques in the diagnosis of EGGCTs at the authors' institution.

METHODS

The laboratory information system was queried over a period of 10 years (2012-2022) to identify all cytology cases diagnosed on fluid cytology, FNA, and/or small-core biopsy as germ cell tumors in extragonadal locations. Patient demographics, tumor location, serum tumor marker levels, cytopathologic diagnosis, and follow-up surgical resection data were reviewed and correlated.

RESULTS

A total of 35 cases from 32 patients (all males) were identified. Thirty specimens contained satisfactory material for diagnosis (86%) and five were less than optimal for evaluation (14%). Despite this, all cases had clinically useful cytopathologic diagnoses. A total of 19 cytology cases (16 patients) had follow-up resection specimens available. Of these, 11 patients underwent preoperative chemotherapy. Nine patients showed no evidence of residual tumor and two showed histologic concordance. Of the five patients who did not have preoperative chemotherapy, all showed concordant histologic diagnoses.

CONCLUSIONS

Cytology can provide a reliable, accurate method for diagnosing EGGCTs. The practice of preoperative (neoadjuvant) chemotherapy places an extreme importance on the initial cytopathologic diagnosis because the majority of patients with follow-up resection in this series showed no residual tumor.

Advanced biomedical imaging for accurate discrimination and prognostication of mediastinal masses

BACKGROUND

To investigate the potential of radiomic features and dual-source dual-energy CT (DECT) parameters in differentiating between benign and malignant mediastinal masses and predicting patient outcomes.

METHODS

In this retrospective study, we analysed data from 90 patients (38 females, mean age 51 ± 25 years) with confirmed mediastinal masses who underwent contrast-enhanced DECT. Attenuation, radiomic features and DECT-derived imaging parameters were evaluated by two experienced readers. We performed analysis of variance (ANOVA) and Chi-square statistic tests for data comparison. Receiver operating characteristic curve analysis and Cox regression tests were used to differentiate between mediastinal masses.

RESULTS

Of the 90 mediastinal masses, 49 (54%) were benign, including cases of thymic hyperplasia/thymic rebound (n = 10), mediastinitis (n = 16) and thymoma (n = 23). The remaining 41 (46%) lesions were classified as malignant, consisting of lymphoma (n = 28), mediastinal tumour (n = 4) and thymic carcinoma (n = 9). Significant differences were observed between benign and malignant mediastinal masses in all DECT-derived parameters (p ≤ .001) and 38 radiomic features (p ≤ .044) obtained from contrast-enhanced DECT. The combination of these methods achieved an area under the curve of .98 (95% CI, .893-1.000; p < .001) to differentiate between benign and malignant masses, with 100% sensitivity and 91% specificity. Throughout a follow-up of 1800 days, a multiparametric model incorporating radiomic features, DECT parameters and gender showed promising prognostic power in predicting all-cause mortality (c-index = .8 [95% CI, .702-.890], p < .001).

CONCLUSIONS

A multiparametric approach combining radiomic features and DECT-derived imaging biomarkers allows for accurate and noninvasive differentiation between benign and malignant masses in the anterior mediastinum.

Approach to Imaging of Mediastinal Masses

Mediastinal masses present a diagnostic challenge due to their diverse etiologies. Accurate localization and internal characteristics of the mass are the two most important factors to narrow the differential diagnosis or provide a specific diagnosis. The International Thymic Malignancy Interest Group (ITMIG) classification is the standard classification system used to localize mediastinal masses. Computed tomography (CT) and magnetic resonance imaging (MRI) are the two most commonly used imaging modalities for characterization of the mediastinal masses.

Analysis of prognostic factors and establishment of prognostic model for primary mediastinal germ cell tumors: a case controlled study

BACKGROUND

The overall prognosis of primary mediastinal germ cell tumors (PMGCTs) is poor and the associated prognostic factors are not fully understood. Our goal was to investigate the prognostic factors of PMGCTs and to develop a validated prognostic prediction model.

MATERIALS AND METHODS

A total of 114 PMGCTs with specific pathological types were included in this study. Clinicopathological characteristics of nonseminomatous PMGCTs and mediastinal seminomas were compared using the χ2 or Fisher's exact test. Independent prognostic factors of nonseminomatous PMGCTs screened using the univariate and multivariate Cox regression analysis were then used to generate a nomogram. The predictive performance of the nomogram was evaluated using the concordance index, decision curve, and the area under the receiver operating characteristic curve (AUC) and validated by bootstrap resampling. The Kaplan-Meier curves of independent prognostic factors were analyzed.

RESULTS

This study included 71 cases of nonseminomatous PMGCTs and 43 cases of mediastinal seminomas. The 3-year overall survival rates for nonseminomatous PMGCTs and mediastinal seminomas patients were 54.5 and 97.4%, respectively. The overall survival prognostic nomogram for nonseminomatous PMGCTs was established by integrating independent prognostic factors, including the Moran-Suster stage, white blood cell, hemoglobin, and platelet-lymphocyte ratio. The nomogram demonstrated good performance with a concordance index of 0.760 and the 1-year and 3-year AUC values of 0.821 and 0.833, respectively. These values were better than those of the Moran-Suster stage system. The bootstrap validation had an AUC of 0.820 (0.724-0.915) and showed a well-fitting calibration curve. Besides, patients with mediastinal seminomas showed favorable clinical outcomes and all the nine patients received neoadjuvant therapy and postoperative surgery achieved pathological complete response.

CONCLUSION

A nomogram based on staging and blood routine examination results was established to accurately and consistently predict the prognosis of patients with nonseminomatous PMGCTs.

The Utility of Fine Needle Aspiration (FNA) Biopsy in the Diagnosis of Mediastinal Lesions

Fine needle aspiration is a minimally invasive, low-morbidity, and cost-efficient technique for the sampling of mediastinal lesions. Additionally, ancillary testing on FNA samples can be used for the refinement of diagnoses and for treatment-related purposes (flow cytometry, cytogenetics, immunohistochemistry, and molecular diagnostics). Mediastinal lesions, however, can show a variety of lineages and morphologic features, giving rise to diagnostic dilemmas. As a result, the differential diagnosis can vary widely and becomes especially challenging due to the smaller sample size on FNA and the variability in component sampling. For appropriate patient management and to determine the correct treatment strategies, accurate pathologic diagnoses are paramount. In this review, we present the cytomorphologic features together with the immunophenotypic findings of mediastinal lesions, with emphasis on the diagnostic challenges and pitfalls in FNA cytology samples, including smears and cell block sections.

A Challenging Case of Heart Displacement by a Large Mediastinal Germ Cell Tumor

Mediastinal germ cell tumors (GCTs) are rare and aggressive cancers originating from the germ cells in the mediastinum. Early detection and treatment are vital due to their high potential for metastasis and recurrence. We present a case of a 28-year-old man who exhibited a cough and shortness of breath. Laboratory tests revealed elevated tumor markers, alpha-fetoprotein, and beta-human chorionic gonadotropin. Imaging studies displayed a large mediastinal mass, causing the right displacement of the mediastinum and cardiac tamponade. The biopsy confirmed a non-seminomatous GCT, specifically a yolk sac tumor. The patient experienced pericardial effusion and cardiac tamponade after receiving two cycles of etoposide and cisplatin chemotherapy. To relieve the tamponade, an emergency pericardiocentesis was performed malignant GCTs necessitate prompt diagnosis and treatment and utilizing multimodal therapy such as chemotherapy to achieve tumor control. Due to the high risk of metastasis, vigilant surveillance for recurrence is essential, emphasizing the need for specific criteria for accurate early detection.

Mediastinal high-grade vasculogenic mesenchymal tumour with seminoma: a case report and literature review

Germ cell tumours with somatic-type solid malignancy (GCT-STM) are a rare disease of the mediastinum. Recently, a cohort of vasculogenic mesenchymal tumour (VMT)-nonseminoma cases with different prognoses were recognized and reported. Here, we report a case of mediastinal high-grade VMT with a seminoma. A 16-year-old male had a fever, chest tightness and fatigue. Chest CT showed a 7.5 cm×5.3 cm solid mass in the right anterior mediastinum. The serum levels of alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (β-HCG) and carcinoembryonic antigen (CEA) were within the normal range. Tumorectomy was performed. The tumour was irregular, and no capsule was found. The cut surface was greyish white and greyish brown with medium consistency. There were foci of bleeding and necrosis. Microscopic histology showed prominent vascular proliferation, which was lined by mildly atypical endothelial cells in a cellular stroma with significant cytologic atypia. The vascular spectrum varied from crevice-like or antler-like thin- to thick-walled vessels. Beyond the tumour area, inside the remnant thymus tissues, there were small clusters of polygonal tumour cells with clear cytoplasm, distinct cell membranes, and round to polygonal nuclei with prominent nucleoli that were positive for Oct4, PLAP, SALL4 and CD117. The patient did not receive any treatments pre- or postoperation, and his condition was stable without progression after 14 months of follow-up evaluation. Here, we added a new entity of GCT-STM of the mediastinum composed of VMT and seminoma. A better understanding of the pathological features of GCT-VMT could help pathologists improve their awareness of these rare diseases.

[Mediastinal tumors : Diagnosis and treatment of the most common tumor entities]

The mediastinum is defined as the space formed ventrally by the sternum, dorsally by the spine, and laterally by the mediastinal pleura. A mediastinal mass is frequently an incidental finding. The wide spectrum of underlying diseases and the anatomic proximity to central structures makes diagnosis and treatment challenging. In many cases, the combination of anamnesis, physical examination, imaging and laboratory tests already provides valuable information about the tumor entity. In addition to diagnostic procedures for histological examination of an unclear mediastinal tumor, radical resection is very important for the prognosis of the patients, especially in the case of tumors of the thymus. Multimodal treatment of advanced tumors that involve adjacent structures is best performed in designated centers.

Hyperechoic mass of the right ventricle in adults: A rare presentation of an intracardiac teratoma

Cardiac teratomas are very rare primary tumors; most are intrapericardial, while a few are intracardiac. Furthermore, most reported intracardiac teratomas are in the pediatric population, with few cases of secondary metastases from testicular teratomas reportedly manifesting in adults. Here, we report a rare case of a mature cystic teratoma in the right ventricle complicated by a bicuspid aortic valve (BAV) in an adult. Echocardiography and enhanced computed tomography (CT) were performed, and the mass was surgically excised. A pathological examination confirmed the diagnosis of a mature cystic teratoma. Meanwhile, mechanical valve replacement of the aortic valve was performed. No tumor recurrence or symptoms occurred in the 2-year follow-up. This is the first report of an adult primary intracardiac teratoma with solid hyperechoic findings on echocardiography and a BAV.

Primary mediastinal germ cell tumors

Mediastinal germ cell tumors share similar histopathological, immunohistochemical, and molecular features with their counterparts in the gonads. Therefore, proper clinical and radiological evaluation of patients with an anterior mediastinal mass becomes essential in the final interpretation of these tumors. The gold standard for the diagnosis of these tumors remains histopathological evaluation. However, immunohistochemical stains and molecular studies also provide an aid in cases in which the histology is not typical. It is also important to keep in mind that a small mediastinoscopic biopsy may not be representative of the entire neoplasm. In this review, we will provide our perspective regarding histopathological diagnosis, staging, immunohistochemical and molecular profile, and briefly family of tumors address pertinent epidemiological, clinical and treatment options. However, the main emphasis is to review the process of pathological assessment in pre and post-treated tumors. Knowledge of the different growth patterns and histological associations is important, mainly when confronted with mediastinoscopic biopsies, which ultimately will determine treatment options.

Immune-related mechanisms and immunotherapy in extragonadal germ cell tumors

Purpose of review

Extragonadal germ cell tumors (EGCTs) are relatively rare tumors, accounting for 1%-5% of all GCTs. In this review, we summarize the current research progress regarding the pathogenesis, diagnosis, and treatment of EGCTs from an immunology perspective.

Recent findings

The histological origin of EGCTs is related to a gonadal origin, but they are located outside the gonad. They show great variation in morphology and can occur in the cranium, mediastinum, sacrococcygeal bone, and other areas. The pathogenesis of EGCTs is poorly understood, and their differential diagnosis is extensive and challenging. EGCT behavior varies greatly according to patient age, histological subtype, and clinical stage.

Summary

This review provides ideas for the future application of immunology in the fight against such diseases, which is a hot topic currently.

Approach to Mediastinal Fine Needle Aspiration Cytology

Mediastinal fine needle aspirations are routinely encountered in cytopathology practice. Mediastinal lesions may pose diagnostic challenges owing to their rarity and locations associated with the complexity of the mediastinal anatomic structures in the thoracic cavity. Diagnosing mediastinal lesions and guiding patient management usually require correlating with clinical and radiologic findings, being familiar with cytomorphologic features and appropriately triaging the diagnostic material for ancillary testing. This review proposes a practical approach to interpret mediastinal fine needle aspirations and emphasizes potential diagnostic pitfalls for mediastinal lesions including benign cysts, thymic neoplasms, lymphoproliferative disorders, germ cell tumors, mesenchymal tumors, and metastatic tumors.

Oleuropein Counteracts Both the Proliferation and Migration of Intra- and Extragonadal Seminoma Cells

Recent and growing literature has reported that oleuropein (OLE), the main polyphenol in olive leaf extract, inhibits tumor cell proliferation and reduces the invasiveness properties of cancer cells; therefore, OLE may play a significant role in the development of new drugs for cancer treatment. These antineoplastic properties have been reported in many experimental cancer models, but the effect of OLE on seminoma cells is yet to be evaluated. In the present study, we demonstrate, for the first time, that OLE reduces cell viability in both intra- and extragonadal TCAM-2 and SEM-1 seminoma cells, respectively, in a dose-dependent manner. As shown by Western-blot analysis, OLE exposure reduced cyclin-D1 expression and upregulated p21^Cip/WAF1, concomitantly affecting the upstream pathway of NF-κB, leading to the reduction of its nuclear content, thereby suggesting that OLE could modulate cell-cycle regulators by inhibiting NF-κB. Moreover, Annexin V staining revealed that OLE induced apoptosis in cancer cells and upregulated the pro-apoptotic factor BAX. Through wound-healing scratch and transmigration assays, we also demonstrated that OLE significantly reduced the migration and motility of TCAM-2 and SEM-1 cells, and downregulated the expression of TGFβ-1, which is known to be the main pro-fibrotic factor involved in the acquisition of the migratory and invasive properties of cancer cells. Collectively, our results indicate that OLE reduces seminoma cell proliferation, promotes apoptosis, and counteracts cell migration and motility. Further studies are needed to explore the molecular mechanisms underlying these observed effects.