Gonadal and extragonadal germ cell tumours in the United States, 1973-2007

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.

Maediastinal germ cell tumors: analysis using hospital-based cancer registry data in Japan

OBJECTIVES

Mediastinal germ cell tumors are rare and few large-scale studies on mediastinal germ cell tumors are reported. We aimed to investigate the clinical characteristics and survival outcomes of patients with mediastinum germ cell tumors in Japan.

METHODS

A hospital-based cancer registry data in Japan was used to identify and enroll patients diagnosed with mediastinal germ cell tumors in 2012-2013. The datasets were registered from 80 institutions.

RESULTS

The selection criteria were met by 123 patients, the majority of whom were male. The median age at diagnosis was 39 years (range 25-89 years) and the most common age groups at diagnosis was 30-39 years, followed by 40-49 years and ≥ 50 years. The histology of non-seminoma (55.3%) was slightly more frequent than that of seminoma (44.7%). The most common histological subtype in non-seminoma was yolk sac tumor, followed by mixed germ cell tumor. The 5-year survival of seminoma and non-seminoma were 96.4% and 57.3%, respectively (p < 0.001). Non-seminomatous mediastinal germ cell tumors, malignant teratomas, mixed germ cell tumors, and yolk sac tumors had comparable survival rates, while those with choriocarcinoma showed the worst prognosis.

CONCLUSIONS

This is the first report showing the clinical characteristics and survival outcomes of mediastinal germ cell tumors in Japan using a real-world large cohort database.

Extragonadal Germ Cell Tumors: A Single Institution Experience with Clinicopathological Correlation

Background. Extragonadal germ cell tumors (EGCTs) are a rare heterogeneous group of tumors without evidence of primary gonadal germ cell tumors. They account for 2%-5% of overall malignancies. EGCTs are often not clinically suspected, making them challenging for pathologists. In this retrospective observational study, we describe our institutional experience among EGCTs with clinicopathological correlation. Materials and methods. All patients diagnosed as EGCTs from January 2014 to April 2023 were collected. All relevant clinical data and serum markers were retrieved from hospital medical records. Histopathology and immunohistochemistry slides were reviewed. Results. The present study included a total of 56 patients; 34 (60%) men and 22 (40%) women with a men-to-women ratio of 1.5:1. Of them, 1 patient had congenital/neonatal EGCTs, 21 patients had prepubertal EGCTs, and 34 had post-pubertal EGCTs. The common sites included are mediastinum (45%), sacrococcyx (18%), retroperitoneum (14%), and central nervous system (12%). The other rare sites were the vagina, liver, colon, and duodenum. The common germ cell tumor included mature teratoma (34%), mixed germ cell tumor (27%), seminoma/germinoma (12%), pure yolk sac tumor (11%), immature teratoma (9%), mature teratoma with somatic tumor (5%), and embryonal carcinoma (2%). All histological diagnoses of germ cell tumors were confirmed with IHC markers like PLAP, CD117 (KIT), AFP, LIN28, CD30, and β-hCG. Pre and posttreatment serum tumor marker levels were available in 37 patients. All our treated patients had a decrease or normal tumor marker levels post-therapy. Conclusion. In our study, a heterogeneous group of germ cell tumors was seen. Most of them were seen in post-pubertal adolescents and young adults. Early intervention by platinum-based combination chemotherapy in seminoma and nonseminomatous germ cell tumors has significantly improved the prognosis of malignant EGCTs similar to their germ cell counterparts.

Neuroendocrine Lesions Arising From Mediastinal Teratoma-A Case Report and Literature Review

Background. Neuroendocrine lesions arising from mediastinal teratomas are rare tumors with only small number of patients reported in literature. The behavior of these lesions appears to be different from traditional neuroendocrine neoplasms. A comprehensive review will be valuable for histologic assessment and treatment planning for similar cases. Case presentation. We present an example of a 57-year-old man who presented with cough. Subsequent work-up revealed an anterior mediastinal mass of 2.1 cm on computed tomography. The patient underwent robot-assisted thoracoscopic thymectomy. Histological examination revealed a mature cystic teratoma with a neuroendocrine component consisting of clusters of tumor cells with round to oval nuclei and a "salt-and-pepper" chromatin pattern. The tumor cells were immunoreactive to cytokeratin, synaptophysin, chromogranin, and INSM1, with a Ki-67 proliferative index of 4%. A histological diagnosis was mature teratoma with well-differentiated low-grade neuroendocrine tumor (carcinoid) was made. The patient was well and without disease after complete surgical excision at 10 months. Literature review. Literature reviewed yielded 13 examples of neuroendocrine lesions arising from mediastinal teratomas. No disease-related mortality was reported, even in lesions with high-grade neuroendocrine, carcinomatous, or immature teratomatous components. Conclusions. Surgical removal is the mainstay of treatment of these lesions, and the presence of a neuroendocrine component does not appear to negatively affect prognosis.

Extragonadal germ cell tumors: A clinicopathologic study with emphasis on molecular features, clinical outcomes and associated secondary malignancies

Extragonadal germ cell tumors (EGCTs) are rare, representing <5% of all germ cell tumors (GCTs). Whilst EGCTs share morphological and immunohistochemical features with their gonadal counterparts, they tend to be more aggressive and are frequently associated with secondary somatic malignancies. The aim of our study was to evaluate the clinical, morphological and immunohistochemical features, and to analyze tumors for chromosomal abnormalities of 12p, in addition to any novel genetic alterations, in a series of EGCTs. Seventy-seven EGCTs were included. Anterior mediastinum was the most common anatomic site, followed by central nervous system, retroperitoneum, sacroccygeal area, and neck. Whole genome SNP array identified isochromosome 12p in 26% of tumors. Additional cytogenetic abnormalities included the presence of gain of chr 21 in 37% of tumors. Somatic-type malignancies were identified in 8% of patients. Disease progression (metastasis and/or recurrence) was documented in 8 patients, most of whom died from their relapse. Three patients who died of disease had somatic-type malignancies. Mediastinal seminomas had a significantly better overall survival when compared to mediastinal non-seminomatous GCTs. Our study demonstrates that EGCTs share similar histologic features, but diverse clinical outcomes compared to their gonadal counterparts. Outcomes vary according to anatomic location and histologic subtypes. Our data corroborate that somatic-type malignancies are frequently encountered in mediastinal EGCTs and that their presence portends a poorer prognosis.

Primary Dysgerminoma of the Uterine Cervix: A Rare Case Report

Introduction

Primary extragonadal germ cell tumors (EGCTs) are a very rare clinical encounter most commonly reported in males. Among females, the placenta, pelvis, uterus, brain, and mediastinum are the most common extragonadal sites and predominantly display nondysgerminoma histology. In this report, we present a case of a primary cervical dysgerminoma in a young female patient. Case Report. An 18-year-old nulligravid woman presented with a 12-month history of vaginal bleeding and discharge. Routine blood tests and serum levels of tumor markers were within normal limits. The chest X-ray was normal. A high-resolution pelvic MRI showed a well-defined lobulated cervicovaginal mass measuring 8 × 6 × 5 cm expanding into the vaginal canal with mild homogenous contrast enhancement. An incisional biopsy was performed vaginally under anesthesia, and histologic findings were consistent with dysgerminoma. A repeat follow-up pelvic MRI was done and showed a reduction in the size of the mass by more than 70%. The patient was treated with 4 cycles of bleomycin, etoposide, and cisplatin chemotherapy. Additional external pelvic beam radiation treatment was administered for a partial response. After 3 months of radiotherapy, a contrast abdominopelvic CT scan showed a recurrent cervicovaginal mass with extension to the pelvic sidewalls. The patient was initiated with ifosfamide, paclitaxel, and cisplatin (ITP) as second-line chemotherapy for a recurrent germ cell tumor but later died from hydronephrosis, chronic anemia, and sepsis.

Conclusion

The uterine cervix is a very unusual site for primary dysgerminoma and can have a very aggressive clinical course. A high index of suspicion and an exhaustive workup are necessary to reach a diagnosis, particularly in a young patient presenting with a cervical lesion.

Spatiotemporal distribution of mediastinal neoplasms: A comprehensive multi-center study

OBJECTIVES

Mediastinal neoplasms are typical but uncommon thoracic diseases with increasing incidence and unfavorable prognoses. A comprehensive understanding of their spatiotemporal distribution is essential for accurate diagnosis and timely treatment. However, previous studies are limited in scale and data coverage. Therefore, this study aims to elucidate the distribution of mediastinal lesions, offering valuable insights into this disease.

MATERIALS AND METHODS

This multi-center, hospital-based observational study included 20 nationwide institutions. A retrospective search of electronic medical records from January 1st, 2009, to December 31st, 2020, was conducted, collecting sociodemographic data, computed tomography images, and pathologic diagnoses. Analysis focused on age, sex, time, location, and geographical region. Comparative assessments were made with global data from a multi-center database.

RESULTS

Among 7,765 cases, thymomas (30.7%), benign mediastinal cysts (23.4%), and neurogenic tumors (10.0%) were predominant. Distribution varied across mediastinal compartments, with thymomas (39.6%), benign cysts (28.1%), and neurogenic tumors (51.9%) most prevalent in the prevascular, visceral, and paravertebral mediastinum, respectively. Age-specific variations were notable, with germ cell tumors prominent in patients under 18 and aged 18-29, while thymomas were more common in patients over 30. The composition of mediastinal lesions across different regions of China remained relatively consistent, but it differs from that of the global population.

CONCLUSION

This study revealed significant heterogeneity in the spatiotemporal distribution of mediastinal neoplasms. These findings provide useful demographic data when considering the differential diagnosis of mediastinal lesions, and would be beneficial for tailoring disease prevention and control strategies.

Extensive surgical resections for rare pleural neoplasms: a single-center experience with a yolk sac tumor and synovial sarcoma

BACKGROUND

Pleural neoplasms are rare and can be subdivided into pleural metastasis and primary pleural neoplasms. Non-mesothelioma primary pleural neoplasms are a diverse group of extremely rare pathologies.

CASE PRESENTATION

In this case series, we describe the presentation and management of two rare primary pleural neoplasms. A first case describes a primary pleural yolk sac tumor treated with neoadjuvant chemotherapy, extended pleurectomy decortication, and hyperthermic intrathoracic chemotherapy. In a second case we describe the management of a primary pleural synovial sarcoma by neoadjuvant chemotherapy and extrapleural pneumonectomy. A complete resection was obtained in both cases and the post-operative course was uncomplicated. No signs of tumor recurrence were noted during follow-up in the first patient. In the second patient a local recurrence was diagnosed 6 months after surgery.

CONCLUSION

Neo-adjuvant chemotherapy followed by extensive thoracic surgery, including hyperthermic intrathoracic chemotherapy, is a feasible treatment strategy for non-mesothelioma primary pleural neoplasms, but careful follow-up is required.

Spontaneous rupture‑induced life‑threatening mediastinal mixed germ cell tumor: A case report and therapeutic considerations

Spontaneous rupture and hemorrhage of mediastinal germ cell tumors is a rare occurrence. In the current report, the case of a 20-year-old male patient who was admitted with chest tightness and dyspnea is presented. An urgent chest CT scan revealed a large tumor in the right anterior mediastinum, measuring ~12 cm in diameter, with associated intratumoral hemorrhage. An emergency thoracotomy was performed to excise the lesion, which revealed that the bleeding was caused by a ruptured tumor. Postoperative pathological findings revealed a mediastinal mixed germ cell tumor consisting of four pathological types: Embryonal carcinoma, seminoma, yolk sac tumor and immature teratoma. Postoperatively, the patient showed marked improvement in the symptoms of dyspnea. However, the follow-up outcome was poor, and the patient succumbed 2 months after surgery. To the best of our knowledge, there are no reports of rupture and hemorrhage involving >4 mixed germ cell tumors. In the present report, the experience of the treatment of the patient is summarized, and literature was reviewed to improve clinicians' awareness of the disease.

Testicular cancer in 2023: Current status and recent progress

Testicular germ cell tumor (GCT) is the most common solid tumor in adolescent and young adult men. Progress in the management of GCT has been made in the last 50 years, with a substantial improvement in cure rates for advanced disease, from 25% in the 1970s to nearly 80%. However, relapsed or platinum-refractory disease occurs in a proportion, 20% of whom will die from disease progression. This article reviews the current evidence-based treatments for extracranial GCT, the acute and chronic toxic effects that may result, and highlights contemporary advances and progress in the field.

Second Hematologic Malignancies Associated With Primary Mediastinal Germ Cell Tumors: A Population-based Study

BACKGROUND

Studies addressing second hematologic malignancies (SHMs) in patients with primary mediastinal germ cell tumors (PMGCTs) are scarce. To better describe this phenomenon, we analyzed a large case series from a population-based registry.

METHODS

The Surveillance, Epidemiology, and End Results database was used to report the clinical characteristics and incidence of SHMs in patients with PMGCT.

RESULTS

Among 1297 PMGCTs, 27 cases (2.08%) of SHM were found, with a median latency period of 12 months (95% CI: 5-41). All SHM occurred in males, 20 of whom (74.1%) had a previous nonseminomatous tumor. Acute myeloid leukemia was the most frequent SHM, accounting for 13 cases, 4 of which were acute megakaryoblastic leukemia that occurred within 5 months of diagnosis. The median survival after the diagnosis of SHM was 6 months (95% CI: 2-41). The risk of SHM was significantly higher than expected for the reference population, with a standardized incidence ratio of 6.21 (95% CI: 3.31-10.62) and an absolute excess risk of 19.19 per 10,000 person-years.

CONCLUSIONS

Patients with PMGCT are at a higher risk of developing SHMs than the general population, particularly acute myeloid leukemia. This risk ranges from synchronous diagnosis of acute megakaryoblastic leukemia to the later onset of other hematological disorders that might be related to PMGCT therapies. Our findings may help create follow-up schedules for patients with PMGCT and raise the level of suspicion surrounding this association.

En bloc resection of an extremely giant mediastinal immature teratoma with somatic-type malignancy: A case report with a brief review of the literature

Primary mediastinum immature teratoma with somatic-type malignant transformation (SM) is extremely rare, and the clinical prognosis is poor. Immature teratoma with SM is difficult to eradicate by chemotherapy due to poor sensitivity; therefore, surgical resection is recommended whenever possible because it may offer better survival.

Primary endodermal sinus tumor originating from the sacral ligament: a case report and review of the literature

BACKGROUND

Endodermal sinus tumor (EST) is a malignant tumor originating from the ovary or testis. In most case, ultrasound examination shows ovarian mass. But there is a special kind of extra-gonadal endodermal sinus tumor, which occur in organs other than gonads with insidious onset. Here we reported a case of endodermal sinus tumor, which originated from the sacral ligament presenting as an acute lower abdominal pain.

CASE PRESENTATION

A 14-year-old girl was admitted to the hospital because of acute lower abdominal pain. The ultrasound showed a mass with 72 mm × 64 mm × 50 mm in Douglas, and there was no abnormality in bilateral ovaries and fallopian tubes. Laparoscopic exploration showed a large amount of blood clots in the pelvic cavity. After removal of the blood, we found rotten fish-like tissue in the left sacral ligament, rapid pathology suggested endodermal sinus tumor. After the operation, we retrospectively examined the value of alpha-fetoprotein (AFP), which was found to be elevated, and post-operative paraffin pathology confirmed the diagnosis. After four cycles of BEP chemotherapy, exploratory laparotomy was performed to remove the visible lesion, but postoperative pathology showed no abnormality. At the one-year follow-up, the patient remained recurrence-free.

CONCLUSION

Extra-gonadal germ cell tumors are rarely reported. When young teenagers complain of acute lower abdominal pain with elevated AFP, but there was no lesion in bilateral ovaries and fallopian tubes, we must think about the possibility of endodermal sinus tumors. Accurate diagnosis facilitates complete resection of lesions and improves patient's outcomes.

Integrated genomic analysis reveals aberrations in WNT signaling in germ cell tumors of childhood and adolescence

Germ cell tumors (GCTs) are neoplasms of the testis, ovary and extragonadal sites that occur in infants, children, adolescents and adults. Post-pubertal (type II) malignant GCTs may present as seminoma, non-seminoma or mixed histologies. In contrast, pre-pubertal (type I) GCTs are limited to (benign) teratoma and (malignant) yolk sac tumor (YST). Epidemiologic and molecular data have shown that pre- and post-pubertal GCTs arise by distinct mechanisms. Dedicated studies of the genomic landscape of type I and II GCT in children and adolescents are lacking. Here we present an integrated genomic analysis of extracranial GCTs across the age spectrum from 0-24 years. Activation of the WNT pathway by somatic mutation, copy-number alteration, and differential promoter methylation is a prominent feature of GCTs in children, adolescents and young adults, and is associated with poor clinical outcomes. Significantly, we find that small molecule WNT inhibitors can suppress GCT cells both in vitro and in vivo. These results highlight the importance of WNT pathway signaling in GCTs across all ages and provide a foundation for future efforts to develop targeted therapies for these cancers.

Primary mediastinal germ cell tumors (PMGCT): A real-world analysis from a tertiary cancer care centre in India

BACKGROUND

Primary mediastinal GCT (PMGCT) is a rare entity and comprises 10-15% of all mediastinal tumors . We present our institutional experience of MGCT treated with multimodality management.

MATERIALS AND METHODS

We conducted a retrospective analysis between 2010 to 2020 of all mediastinal germ cell tumors registered at our center. Data on patient demographics, treatments received, treatment toxicities and response were recorded. Overall survival and relapse free survival were estimated using Kaplan-Meier methods.

RESULTS

A total of 30 patients were identified. The median age was 25.5 (range, 18-45) years. Common presenting features included cough (70%) and shortness of breath (70%) . Histology wise, 60% patients were non seminomatous histology whereas 33.3% patients were Seminoma.Twenty seven (90%) patients received chemotherapy as the first-line treatment, of whom five patients (16.6%) underwent surgery and radiation therapy subsequently. Median follow-up was 26.9 months. Thirteen patients (43.3%) had complete response (43.3%) and 8 patients had partial response (26.7%), while three patients (5.5%) had progressive disease. Three year relapse free survival rate was 69.6% (95% confidence interval [CI], 42.8-85.6%). Overall survival (OS) at 3 years was 73.4% (95% CI, 49.4- 87.3%). Patients with seminoma had a 3 year OS of 90.0% (95% CI, 47.3-98.5%) compared to those with non-seminoma (63.53% [95% CI, 32.3-83.3%]).

CONCLUSIONS

Multiagent chemotherapy is the backbone of treatement in PMGCT. Seminomatous PMGCT have excellent prognosis, while further improvement is needed in those with non-seminomatous tumor.

Reprint of: somatic-type malignancies in testicular germ cell tumors

The development of somatic-type malignancy (SM) in testicular germ cell tumor represents a major challenge in the diagnosis and treatment of testicular cancer. Most SMs are derived from teratoma, and the remainder is associated with yolk sac tumor. They occur more frequently in metastases than in primary testicular tumors. SMs demonstrate a variety of histologic types, including sarcoma, carcinoma, embryonic-type neuroectodermal tumor, nephroblastoma-like tumor, and hematologic malignancy. Sarcoma, particularly rhabdomyosarcoma, accounts for the majority of SMs in the primary testicular tumors, whereas carcinoma, particularly adenocarcinoma, is the most common SM in metastases. Although SMs derived from testicular germ cell tumors mimic their histologic counterparts in other organs with overlapping immunohistochemical profiles, isochromosome 12p is present in most SMs, which can be useful in the differential diagnosis. The presence of SM in the primary testicular tumor may not worsen the outcome, but the development of SM in metastasis is associated with a poor prognosis. Furthermore, somatic-type carcinoma is likely associated with a worse prognosis than somatic-type sarcoma. Although SMs respond poorly to the cisplatin-based chemotherapy, timely surgical resection is an effective treatment for most patients.

Primary Undifferentiated Neoplasm of the Left Arm with Characteristics of Extragonadal Germ Cell Tumor and High-Grade Sarcoma

A previously healthy man in his late 20s was diagnosed with a primary undifferentiated non- metastatic tumor of the left arm. After a biopsy, a clear pathological diagnosis could not be established. The tumor had positive immunohistological markers for both an extragonadal germ cell tumor and a high-grade sarcoma. Given the presumed germ cell etiology, he was started on empiric chemotherapy with etoposide and cisplatin. After a few cycles, the tumor showed dramatic response. However, due to poor patient follow- up, it progressed to massive size with severe compromise of the joint and critical neurovascular structures, which led to the decision for limb amputation. Post-surgical checkups showed no recurrence of the primary tumor or metastasis. This is the first report in the literature showing a tumor with these histological characteristics that responded to platinum-based therapy. It provides evidence for the need of more specific markers for the pathological evaluation of undifferentiated neoplasms.

Metastatic yolk sac tumor masquerading as multifocal hepatocellular carcinoma in a young adult: A case report

Primary yolk sac tumor of the liver is very rare and can present as multifocal liver lesions. Multifocal nature may mimic other diagnoses such as hepatocellular carcinoma. Early recognition and therapeutic intervention are important as the prognosis of metastatic yolk sac tumors is poor. We present a case of a young adolescent who presented with bleeding per rectum abdominal pain and multiple liver lesions.

Metastatic yolk sac tumor masquerading as multifocal hepatocellular carcinoma in a young adult: A case report

Primary yolk sac tumor of the liver is very rare and can present as multifocal liver lesions. Multifocal nature may mimic other diagnoses such as hepatocellular carcinoma. Early recognition and therapeutic intervention are important as the prognosis of metastatic yolk sac tumors is poor. We present a case of a young adolescent who presented with bleeding per rectum abdominal pain and multiple liver lesions.

Germ Cell Tumors of the Ovary: A Review

Ovarian germ cell tumors are a diverse group of benign and malignant neoplasms that occur in a wide age range, but with a predilection for younger age group. The majority are represented by the frequently encountered mature cystic teratomas. Malignant germ cell tumors are uncommon, and in some cases have a characteristic clinical presentation. However, from a histologic standpoint these tumors can sometimes be challenging to diagnose due to overlapping morphology with epithelial, and in some cases sex cord tumors. In these cases, a panel of immunohistochemical stains often facilitates the correct diagnosis. This review article discusses the clinicopathologic findings and pertinent ancillary studies of both common and uncommon germ cell tumors of the ovary.

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.

Genomic features of mediastinal germ cell tumors: a narrative review

BACKGROUND AND OBJECTIVE

Germ cell tumors (GCTs) are uncommon malignancies generally originating from gonads. However, about 5% of GCTs arise outside the gonad (extragonadal), of which 80% develop from the mediastinum. While the prognosis of seminomas is not affected by the gonadal or extragonadal primary location, the prognosis of nonseminoma primary mediastinal GCTs (NS-PMGCTs) is poor, compared to its gonadal counterpart with an estimated 5-year overall survival of about 50%. The current treatments are sub-optimal to increase the cure rate of these rare GCTs. Therefore, molecular insights into these tumors would be valuable to develop novel therapies. The main objective of this review is to describe and dissect the genomic features associated with primary mediastinal GCTs (PMGCTs), highlighting the more frequent genomic alterations and their correlation with clinical outcomes.

METHODS

We conducted a narrative review of the English literature available in PubMed and Google Scholar between 1982 and 2021, including meta-analyses, systematic reviews, case series and case reports regarding the genomic and clinical features of PMGCTs. We analyzed the available data to describe the molecular characteristics of PMGCTs compared to testicular GCTs (TGCTs), highlighting the most relevant biological and prognostic factors.

KEY CONTENT AND FINDINGS

The high percentage of platinum resistance, the unique association with hematologic malignancies (HMs) and other malignancies, the higher prevalence of P53 mutations, and a distinct genomic landscape characterize this rare disease.

CONCLUSIONS

Although some studies have unveiled recurrent molecular alterations in PMGCTs, few are particularly suitable for targeted therapy. Due to the rarity of PMGCTs, data sharing and the creation of an international consortium would be helpful to have a better understanding of the molecular drivers of these tumors.

Extragonadal Germ Cell Tumors of the Mediastinum and Retroperitoneum: A Surveillance, Epidemiology, and End Results-based Study

OBJECTIVES

Extragonadal germ cell tumors (EGCT) are a rare entity, most of them being located in the mediastinum and retroperitoneum. Information on these tumors is scarce, requiring carrying out large population-based studies to better understand these diseases. We aimed to determine the clinical features and prognosis of patients with EGCT of the mediastinum and retroperitoneum.

MATERIALS AND METHODS

Demographic and clinicopathological features of patients diagnosed with EGCT of the mediastinum and retroperitoneum from 1975 to 2016 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database.

RESULTS

A total of 1674 patients were included, 1297 (77.5%) of mediastinal origin and 377 (22.5%) of retroperitoneum. Nonseminomatous tumors (56.3%) were slightly more frequent than seminomas (43.7%) with similar distribution between mediastinum and retroperitoneum. After a median follow-up of 137 months, the median overall survival was 263 months (95% CI, 220-296) whereas the median cause-specific survival (CSS) has still not been reached. The 10-year overall survival and CSS were 57.4% (95% CI, 55-59.7) and 63% (95% CI, 60.6-65.2) respectively. Multivariate analysis showed that older age, mediastinal location, nonseminomatous histology, and distant disease at diagnosis were independent prognostic factors correlated with a worse prognosis. Patients with mediastinal choriocarcinoma and embryonal carcinoma have the worst prognosis, both with a median CSS of only 12 months.

CONCLUSIONS

Despite a decreasing incidence observed in recent decades, EGCT continues to represent a challenge for oncologists. The prognosis of choriocarcinoma and embryonal carcinoma of the mediastinum remains poor and treatment strategies need to be improved urgently.

Primary immature teratoma in the liver with growing teratoma syndrome and gliomatosis peritonei: a rare case report

Background

Primary liver immature teratoma is extremely rare and only 4 cases have been reported, let alone with growing teratoma syndrome (GTS) and/or gliomatosis peritonei (GP).

Case presentation

Here, we report a case of a 44-year-old female presenting with progressive abdominal distension and elevated serum alpha fetal protein (AFP) level. CT/MRI scans revealed a large cystic-solid mass in the right lobe of the liver, accompanied with implant or metastasis in the abdominal cavity. Pathologic examination at biopsy suggested immature teratoma. After 4 cycles of chemotherapy, an MRI showed a slight increase in tumor size. Therefore, surgical resection of the right lobe of the liver was performed. The final histological diagnosis was a mature teratoma (tumor size 28 cm × 14 cm × 13 cm), with no residual immature component, and the diagnosis of GTS was considered. The patient continued to receive 2 courses of postoperative chemotherapy. An abdominal CT scan revealed innumerable miliary nodules in bilateral adnexal areas 2 months after surgery. Histologically, large numbers of mature glia were observed, supporting the diagnosis of GP.

Conclusions

We report for the first time a case of primary liver immature teratoma with GTS and GP in an adult. Longer follow-up is needed to assess definitive efficacy.

Somatic-Type Malignancies in Testicular Germ Cell Tumors

The development of somatic-type malignancy (SM) in testicular germ cell tumor represents a major challenge in the diagnosis and treatment of testicular cancer. Most SMs are derived from teratoma, and the remainder is associated with yolk sac tumor. They occur more frequently in metastases than in primary testicular tumors. SMs demonstrate a variety of histologic types, including sarcoma, carcinoma, embryonic-type neuroectodermal tumor, nephroblastoma-like tumor, and hematologic malignancy. Sarcoma, particularly rhabdomyosarcoma, accounts for the majority of SMs in the primary testicular tumors, whereas carcinoma, particularly adenocarcinoma, is the most common SM in metastases. Although SMs derived from testicular germ cell tumors mimic their histologic counterparts in other organs with overlapping immunohistochemical profiles, isochromosome 12p is present in most SMs, which can be useful in the differential diagnosis. The presence of SM in the primary testicular tumor may not worsen the outcome, but the development of SM in metastasis is associated with a poor prognosis. Furthermore, somatic-type carcinoma is likely associated with a worse prognosis than somatic-type sarcoma. Although SMs respond poorly to the cisplatin-based chemotherapy, timely surgical resection is an effective treatment for most patients.

A Subset of SMARCB1 (INI-1)-deficient vulvar neoplasms express germ cell markers

AIMS

SMARCB1 (INI-1)-deficient vulvar neoplasms comprise a group of rare tumours that include epithelioid sarcoma (ES), myoepithelial carcinoma (MEC), the recently described myoepithelioma-like tumour of the vulvar region (MELTVR), and sarcomas that are difficult to classify. It has been suggested that so-called vulvar yolk sac tumours (YST) may represent morphologic variants of SMARCB1-deficient tumours; thus, we investigated the immunoreactivity of germ cell markers in SMARCB1-deficient vulvar neoplasms.

METHODS AND RESULTS

Ten SMARCB1-deficient vulvar neoplasms were stained with germ cell tumour markers (SALL4, glypican-3, OCT3/4, and AFP) and re-reviewed for morphologic features. The tumours occurred in adult females (median age 41 years) and included ES (n = 7), MELTVR (n = 2), and MEC (n = 1). All cases showed loss of SMARCB1 expression. Four cases (40%) were focally positive for SALL4 in areas with morphology of typical-appearing ES. One of these cases also showed focal staining for OCT3/4. One ES showed a transition from typical-appearing ES to YST-like morphology, with diffuse expression of SALL4 and glypican-3, and focal expression of AFP, in these latter areas. All other tested cases were negative for AFP.

CONCLUSION

Our study reveals that SALL4, glypican-3, and OCT3/4 are positive in a subset of SMARCB1-deficient vulvar neoplasms, which may pose a diagnostic challenge and result in consideration of a germ cell tumour. We also highlight a case with transition from ES to YST-like morphology, lending further support that YSTs of the vulva are somatically derived SMARCB1-deficient neoplasms and do not represent true germ-cell neoplasia.

Standard versus high-dose chemotherapy in mediastinal germ cell tumors: a narrative review

OBJECTIVE

The aim of this review is to analyze feasibility and toxicities of high-dose chemotherapy (HDCT) in comparison to standard dose chemotherapy (SDCT) in patients affected by mediastinal germ cell tumors (MGCTs), discussing factors that may affect therapeutic choices, such as: management of residual disease, early response predictors for chemotherapeutic efficacy and determinants of chemotherapeutic resistance. In this review, we discuss the main clinical experiences with HDCT and SDCT in germ cell tumor (GCT) patients specifically in those affected by MGCT.

BACKGROUND

MGCTs represent a very small subset characterized by a poor prognosis, despite improvements in their clinical management and in understanding their biology. From early 1970s, HDCT has become an alternative to SDCT for both first-line and salvage therapeutic settings in advanced GCT patients. Several HDCT schedules-either cisplatin or carboplatin-based-have been tested so far, both in clinical randomized trial and in single-center experiences, with divergent results in terms of clinical outcomes and tolerability. Moreover, the majority of these studies included, but were not exclusively designed for, advanced MGCT patients, making difficult to infer data for this specific subset.

METHODS

an extended review of literature through PubMed was conducted using the keywords "mediastinal germinal cell tumors", "standard dose chemotherapy" and "high dose chemotherapy".

CONCLUSIONS

HDCT regimens could not be considered to date a standard option as first-line therapy in advanced MGCT patients, whilst they could be an alternative to SDCT regimens in relapsed tumors after proper patient selection.

Vulvar Yolk Sac Tumors Are Somatically Derived SMARCB1 (INI-1)-Deficient Neoplasms

So-called primary yolk sac tumors of the vulva are very rare and often have an aggressive disease course. Their molecular features have not been previously characterized. There is also a well-documented group of SMARCB1 (INI-1)-deficient vulvar neoplasms, which includes proximal-type epithelioid sarcoma and myoepithelial carcinoma. Until now, "vulvar yolk sac tumors" and SMARCB1-deficient neoplasms were considered unrelated diseases. After reviewing an index case of a vulvar yolk sac tumor with loss of SMARCB1 by immunohistochemistry, we retrospectively identified 2 additional cases diagnosed as vulvar yolk sac tumors. Patient ages were 34, 32, and 25 years old, and 2 tumors were associated with a pregnancy. All 3 cases showed morphology typical of a yolk sac tumor, and by immunohistochemistry all were positive for SALL4, glypican-3, keratins, and lacked CD34 positivity. All tumors also demonstrated loss of SMARCB1 in tumor cells. Targeted molecular profiling was performed in 2 cases and identified 2 copy deletion of SMARCB1, without genomic alterations typically seen in gonadal yolk sac tumors. In the third case, isochromosome 12p was not identified by fluorescence in situ hybridization. All 3 patients had either local recurrences or distant metastases, and 2 died of disease. One patient had progressive disease while receiving the enhancer of zeste homolog 2 inhibitor tazemetostat. Overall, these findings suggest that vulvar tumors with pure yolk sac-like morphology may represent morphologic variants of SMARCB1-deficient tumors and not veritable germ cell neoplasia. This potential reclassification may have both prognostic and treatment implications and warrants study of additional extragonadal yolk sac tumors.

Yolk Sac Tumor of the Omentum: A Case Report and Literature Review

This is a case report of a rare finding of an extragonadal yolk sac tumor in a 37-year-old patient who presented with shortness of breath and abdominal bloating. During imaging and staging surgery, the findings were strongly suggestive of an extragonadal advanced tumor presenting with peritoneal dissemination, predominantly affecting omentum, with no clear primary origin. Histology revealed an extragonadal yolk sac tumor in a pure form outside the ovaries. Lacking an obvious origin elsewhere, the tumor was highly suspected to have truly originated from the omentum. The patient underwent surgery and four cycles of chemotherapy consisting of cisplatin, etoposide, and bleomycin. One-year outpatient follow-up thereafter showed no relapse. We herein discuss a possible site of the tumor origin and its development, as well as diagnostic challenges and disease prognosis.

Retroperitoneal extragonadal germ cell tumor with duodenal infiltration: A challenging endo‐luminal tissue diagnosis

A 32‐year‐old Malay male was referred to our hospital for a second opinion. An abdominal and pelvic CT scan at the previous medical facility showed a large retroperitoneal tumor, which was subjected to ultrasound‐guided fine‐needle aspiration cytology (FNAC) with a provisional diagnosis of malignant lymphoma. However, after reviewing the existing results, a repeat biopsy was deemed necessary and this was performed endoluminally via gastroduodenoscopy in view of the close proximity of the tumor and the third part of the duodenum. The first biopsy failed to detect any abnormal cells, but a repeat biopsy with supporting evidence from other laboratory results led to a final diagnosis of extragonadal germ cell tumor (GCT) with duodenal infiltration.

Urachal yolk sac tumor penetrating the bladder as a diagnostic challenge: a case report and review of the literature

Background

Yolk sac tumor (YST) is a germ cell tumor. It is primarily located in the gonads but can also occur extragonadally (extragonadal yolk sac tumor - EGYST), most commonly in the pelvis, retroperitoneum or mediastinum. Only a few YSTs of the urachus have been described.

Case report

We present a rare case report of a 37-year-old male with episodes of macroscopic hematuria. The histological specimen obtained by transurethral resection showed a solid, and in some parts papillary infiltrative, high-grade tumor with numerous areas of marked nuclear atypia and clear invasion between the detrusor bundles. Glandular pattern has been observed in only minority of the tumor. Immunohistochemistry showed significant positivity for GPC3, SALL4 and cytokeratins AE1/AE3, while KRT7 and GATA3 were negative. We concluded that the biopsy findings were consistent with urothelial carcinoma with infrequent YST differentiation. In definitive surgical specimens we found a malignant epithelial, glandular and cystically arranged tumor of germinal appearance arising from urachus. The surrounding urothelium was free of invasive or in situ tumor changes. We reclassified the tumor as a urachal YST.

Conclusion

EGYST was suspected because glandular and hepatoid structures were found, but the presence of these structures should be verified by immunohistochemistry.

Survival Outcomes of Patients With Mediastinal Germ Cell Tumors: Experience of a Cancer Center in South America

PURPOSE

Mediastinal germ cell tumors (GCT) are rare neoplasms associated with poor survival prognosis. Due to their low incidence, limited information is available about this disease in South America. The objective of this study is to report the clinical characteristics and outcomes of patients with mediastinal GCT in a cancer center in Colombia.

MATERIALS AND METHODS

We conducted a retrospective analysis of patients with mediastinal GCT treated at the National Cancer Institute at Bogota (Colombia) between 2008 and 2020. Survival curves were presented using the Kaplan-Meier method. Chi-square and Cox proportional hazard model tests were used for data analysis.

RESULTS

Sixty-one patients were included in the study. Of them, 60 were male and 51 (83.6%) of whom had non-seminomatous germ cell tumors (NSGCT). Twenty-nine patients (47.5%) presented with superior vena cava syndrome, and 18 (29.5%) patients had extrapulmonary metastatic involvement. The three-year overall survival (OS) of NSGCT patients was 26%. The 3-year OS of NSGCT patients who underwent surgical resection of residual mediastinal mass after chemotherapy was 59%. Non-surgical management after first-line chemotherapy was associated with a worse survival prognosis in NSGCT patients (p = 0.002). Ten patients with mediastinal seminomatous germ cell tumors (SCGT) achieved a 3-year OS of 100%.

CONCLUSION

Mediastinal NSGCT had poor outcomes. Surgery of the residual mass after first-line chemotherapy seems to improve the outcome of NSGCT patients. Advanced disease at presentation may reflect inadequate access to reference cancer centers in Colombia and potentially explain poor survival outcomes in this cohort. On the other hand, mediastinal SCGT is a biologically different disease; most patients will achieve disease remission and long-term survival with first-line chemotherapy.

How to classify, diagnose, treat and follow-up extragonadal germ cell tumors? A systematic review of available evidence

PURPOSE

To present the current evidence and the development of studies in recent years on the management of extragonadal germ cell tumors (EGCT).

METHODS

A systematic literature search was conducted in Medline and the Cochrane Library. Studies within the search period (January 2010 to February 2021) that addressed the classification, diagnosis, prognosis, treatment, and follow-up of extragonadal tumors were included. Risk of bias was assessed and relevant data were extracted in evidence tables.

RESULTS

The systematic search identified nine studies. Germ cell tumors (GCT) arise predominantly from within the testis, but about 5% of the tumors are primarily located extragonadal. EGCT are localized primarily mediastinal or retroperitoneal in the midline of the body. EGCT patients are classified according to the IGCCCG classification. Consecutively, all mediastinal non-seminomatous EGCT patients belong to the "poor prognosis" group. In contrast mediastinal seminoma and both retroperitoneal seminoma and non-seminoma patients seem to have a similar prognosis as patients with gonadal GCTs and metastasis at theses respective sites. The standard chemotherapy regimen for patients with a EGCT consists of 3-4 cycles (good vs intermediate prognosis) of bleomycin, etoposid, cisplatin (BEP); however, due to their very poor prognosis patients with non-seminomatous mediastinal GCT should receive a dose-intensified or high-dose chemotherapy approach upfront on an individual basis and should thus be referred to expert centers Ifosfamide may be exchanged for bleomycin in cases of additional pulmonary metastasis due to subsequently planned resections. In general patients with non-seminomatous EGCT, residual tumor resection (RTR) should be performed after chemotherapy.

CONCLUSION

In general, non-seminomatous EGCT have a poorer prognosis compared to testicular GCT, while seminomatous EGGCT seem to have a similar prognosis to patients with metastatic testicular seminoma. The current insights on EGCT are limited, since all data are mainly based on case series and studies with small patient numbers and non-comparative studies. In general, systemic treatment should be performed like in testicular metastatic GCTs but upfront dose intensification of chemotherapy should be considered for mediastinal non-seminoma patients. Thus, EGCT should be referred to interdisciplinary centers with utmost experience in the treatment of germ cell tumors.

Metachronous testicular tumour recurrence in extra-gonadal germ cell tumour: A case report and review of the literature

A 24-year-old male presented in 2014 with left sided abdominal pain and a palpable abdominal mass. After appropriate investigation a diagnosis of an extra-gonadal germ cell tumour was made and he was treated with platinum based chemotherapy. He then underwent retroperitoneal lymph node dissection due to residual disease identified on imaging with no specific tissue type identified on the histological sample. In early 2019 he presented to his General Practitioner with a left sided testicular lump and was diagnosed with non-seminomatous germ cell tumour of the testis, an uncommon condition; metachronous testicular tumour.

Level of Evidence: 5

Management of a Primary Retroperitoneal Yolk Sac Tumor

Patient: Male, 31-year-old

Final Diagnosis: Primary retroperitoneal yolk sac tumor

Symptoms: Lower abdominal pain

Medication:—

Clinical Procedure: —

Specialty: Oncology • Surgery

Primary mediastinal germ cell tumours: an immunohistochemical and molecular diagnostic approach

AIMS

Primary mediastinal germ cell tumours (PMGCTs) are rare mediastinal neoplasms and their diagnosis can be challenging due to small biopsy samples. The aim of this study was to elaborate a diagnostic algorithm using immunohistochemical stainings with focus on novel markers and molecular analysis of isochromosome 12p [i(12p)].

METHODS AND RESULTS

Paraffin-embedded tissues of 32 mediastinal tumours were analysed using immunohistochemical stainings for SALL4, LIN28, OCT3/4, D2-40, CD117, SOX17, SOX2, CD30, ß-hCG, GATA3, FOXA2, GPC3, AFP, TdT, NUT and pan-cytokeratin. Quantitative real-time polymerase chain reaction (qPCR) was performed to investigate i(12p) status. Fifteen seminomas, seven teratomas, one yolk sac tumour, one choriocarcinoma and seven mixed PMGCT were diagnosed. Each entity had different immunohistochemical staining patterns which helped to distinguish them: seminoma (OCT3/4, D2-40, CD117, TdT), embryonal carcinoma (OCT3/4, SOX2), yolk sac tumour (FOXA2, GPC3, AFP) and choriocarcinoma (ß-hCG, GATA3). Mature teratomas stained positive for pan-cytokeratin in epithelial components and focally for SALL4, SOX2, GATA3, D2-40 and FOXA2. Furthermore, a NUT carcinoma mimicking a PMGCT was diagnosed showing a strong nuclear SOX2 and speckled nuclear NUT staining. i(12p) was detected in 24 out of 27 PMGCTs [89%].

CONCLUSION

A diagnostic algorithm is of great importance for a reliable diagnosis of PMGCTs in the usually small tissue biopsy samples. Therefore, a combination of three to four antibodies to identify the correct histological subtype is usually necessary in addition to morphological features. The i(12p) status serves as an additional option to underline germ cell origin in selected cases.

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

Mediastinal germ cell tumors (MGCTs) are the most common extragonadal germ cell tumors (GCTs) and most often arise in the anterior mediastinum with a male predilection. MGCTs also have a predilection for patients with Klinefelter syndrome and possibly other genetic conditions. MGCTs, as GCTs at other extragonadal sites, are thought to arise from germ cells improperly retained during migration along the midline during embryogenesis. Similar to their counterparts in the testes, MGCTs are classified into seminomatous and nonseminomatous GCTs. Seminomatous MGCT represents pure seminoma, whereas nonseminomatous MGCTs encompass pure yolk sac tumors, embryonal carcinoma, choriocarcinoma, mature or immature teratoma, and mixed GCTs with any combination of GCT types, including seminoma. Somatic-type or hematologic malignancies can also occur in association with a primary MGCT. MGCTs share molecular findings with GCTs at other sites, most commonly the presence of chromosome 12p gains and isochromosome i(12p). Treatment includes neoadjuvant chemotherapy followed by surgical resection of residual tumor, with the exception of benign teratomas, which require only surgical resection without chemotherapy. In this review, we highlight and provide an update on pathologic, clinical, and molecular features of MGCTs. Immunohistochemical profiles of each tumor type, as well as differential diagnostic considerations, are discussed.

Pathology of Seminoma Coinciding With Small Lymphocytic Lymphoma/Chronic Lymphocytic Leukemia

We present the case of a 71-year-old male with an incidental diagnosis of seminoma coinciding with small lymphocytic lymphoma/chronic lymphocytic leukemia in the retroperitoneum. This case report illustrates the cytology, histology, immunohistochemistry, flow cytometry, and fluorescence in situ hybridization features of this exceptional case and sheds light on the importance of a collaborative multidisciplinary team in delivering quality patient care. 

A scoping review on the "burned out" or "burnt out" testicular cancer: When a rare phenomenon deserves more attention

The "burned out" or "burnt out" testicular cancer (BTC) indicates the spontaneous and complete regression of a testicular germ cell tumor in the presence of distant metastases at the diagnosis. As this condition was never reviewed systematically, a scoping review was conducted to scrutinize the available literature on clinical and histological features of BTC patients. Medline was searched from inception to 19 April 2020. A virtual cohort of 68 BTC patients was generated. Our findings highlighted some inconsistencies: BTC was diagnosed in 5,9% of patients not showing distant metastases and in 2,9% of patients who did not undergo an orchiectomy. Besides, evidence of residual tumor was found in 22,7% of testis specimens, recognized as seminoma in 40% of cases. The emerged inconsistencies may derive from the lack of an unequivocal definition of BTC. Larger collaborative studies are needed to define the best diagnostic workup and treatment for BTC patients.

Extragonadal germ cell tumor, a report of two cases presenting in the gastrointestinal tract

Germ cell tumors are a heterogeneous group of tumors that can present primarily as gonadal tumors in either a localized or metastatic pattern. Rarely these tumors can initially present at extra-gonadal locations, including the gastrointestinal tract. We report two young male patients who presented with nonspecific gastrointestinal symptoms caused by a mass lesion involving the duodenum. Pathologically, both were confirmed to be germ cell tumors; an unfamiliar initial presentation of germ cell tumors. In both cases, evidence of pre-existing gonadal tumor in the form of a testicular mass and a burned-out tumor with microlithiasis, in the first and second cases, respectively was detected following the confirmed diagnosis of extra-gonadal germ cell tumor. Each patient’s clinical course and outcome emphasizes the importance of a high index of suspicion, timely diagnosis, and appropriate management.

Mediastinal mixed germ cell tumor: A case report and literature review

Mixed germ cell tumor (MGCT) mainly occurs in young women’s ovaries and men’s testicles and rarely occurs outside the gonad. Fewer than 10 cases of mediastinal MGCT are available in PubMed, Embase, and other databases in English, while mediastinal MGCT with three pathological components, such as yolk sac tumor, immature teratoma, and embryonal carcinoma, has not been reported previously. A 12-year-old male sought medical attention for chest discomfort and underwent a computed tomography (CT) scan. A large soft tissue mass occupying most of the left thoracic cavity and mediastinum was detected. A CT-guided biopsy was performed, and an MGCT was diagnosed with pathological components, including yolk sac tumor, immature teratoma, and a small amount of embryonal carcinoma. Due to the large size of the tumor, the patient was treated with an EP regimen (etoposide + cisplatin) and paclitaxel + ifosfamide + cisplatin interstitial chemotherapy. The patient was followed up for 6 months and was alive with the disease. To the best of our knowledge, this is the 10th patient with MGCT in the mediastinum. The incidence of mediastinal MGCT is low, but it should still be considered one of the differential diagnoses of isolated pleural fibroma and neurogenic tumors.

A presumed extragonadal germ cell tumor that turned out to be a gastric cancer-a case report

A solely retroperitoneal mass in males in combination with elevated serum Alpha-Fetoprotein (AFP) and beta-human choriogonadotropin (β-HCG) levels is highly indicative of a metastatic testicular cancer. Although testicular cancers are rare, they represent the most common diagnosed cancer in males between 14 and 40 years. However, in cases without evidence of a primary testicular tumor, the rare diagnosis of a retroperitoneal extragonadal germ cell tumor (EGCT) must be assumed. Here, we describe the first published case of a 66-year-old man presenting with this typical clinical picture and the diagnosis of an AFP and β-HCG producing advanced gastric cancer with retroperitoneal lymph node metastases mimicking a primary retroperitoneal EGCT. The final diagnosis was only made by gastroscopy performed after a CT-guided retroperitoneal lymph node biopsy revealed an adenocarcinoma, suggesting an upper gastrointestinal tract primary origin. However, a specific initial anamnesis and also in the primary staging, including a full-body CT-scan there was no hint for another primary tumor. Only the slightly unusual extension of the retroperitoneal mass up to the ligamentum hepatoduodenale and the pylorus, as well as the atypical age made us question our initial diagnosis. This extraordinary case is of special clinical interest to all practising physicians and once again highlights the importance of keeping rare differential diagnosis such as AFP-producing gastrointestinal tumors in mind.

Single nucleotide polymorphism array and cytogenetic analyses of ovarian teratomas in children

Teratomas are the most common tumors in the ovary during childhood. Previous studies suggested that they may be derived from germ cells at any developmental stage from premeiotic oogonia through meiotic oocytes to post-meiotic ova. The majority of mature teratomas reveal normal karyotypes and immature teratomas show higher frequency of chromosomal abnormalities. We analyzed fresh tissue samples from 25 primary ovarian teratomas and three extraovarian deposits using whole genome single nucleotide polymorphism (SNP) array and karyotype. SNP array detected five patterns of copy neutral loss of heterozygosity (CN-LOH): failure of meiosis I (type I) in 12 tumors, failure of meiosis II (type II) in six tumors, endoreduplication of a haploid ovum (type III) in two tumors, premeiotic error (type IV) in four tumors, and both meiotic I and meiotic II errors in one tumor (type V). Three tumors with type I error had a single chromosome showing meiotic II error, and two tumors with type II error had a single chromosome showing premature sister-chromatid separation in meiosis I. Lack of recombination in multiple chromosomes in meiosis I were common, chromosomes 17, 7, 8, 21, and 22 were most commonly involved. Abnormal karyotypes were observed in four teratomas including +3, del(3q), +7, +8, +12, and i(18q). The extraovarian deposits revealed the same CN-LOH pattern as the primary teratoma. In summary, SNP array reveals the origin of ovarian teratoma and we propose a new mechanism that consecutive meiotic I and II errors occur frequently in ovarian teratomas.

Primary Mediastinal Germ Cell Tumors-The University of Western Ontario Experience

Extragonadal germ cell tumors account for 2–5.7% of germ cell tumors (GCTs). Of these, primary mediastinal GCTs (PMGCTs) are responsible for 16–36% of cases. Given the rarity of these tumors, specific treatment strategies have not been well defined. We report our experience in treating these complex patients. In total, 318 men treated at our institution with chemotherapy for GCTs between 1980 and 2016 were reviewed. PMGCT was defined as clinically diagnosed mediastinal GCT with no evidence of testicular GCT (physical exam/ultrasound). We identified nine patients diagnosed with PMGCT. All patients presented with an anterior mediastinal mass and no gonadal lesion; four patients also had metastatic disease. Median age at diagnosis was 30 years (range, 14–56) and median mass size at diagnosis was 9 cm (range, 3.4–19). Eight patients had non-seminoma and one had pure seminoma. All patients received cisplatin-based chemotherapy initially. Surgical resection was performed in four patients; three patients had a complete resection and one patient was found to have an unresectable tumor. At a median follow-up of 2 years (range, 3 months–28 years) six patients had progressed. Progression-free survival was short with a median of 4.1 months from diagnosis (range 1.5–122.2 months). Five patients died at a median of 4.4 months from diagnosis. One and 5-year overall survivals were 50% and 38%, respectively. PMGCT are rare and aggressive. Our real-life Canadian experience is consistent with current literature suggesting that non-seminoma PMGCT has a poor prognosis despite prompt cisplatin-based chemotherapy followed by aggressive thoracic surgery.

The detection of isochromosome i(12p) in malignant germ cell tumours and tumours with somatic malignant transformation by the use of quantitative real-time polymerase chain reaction

AIMS

Malignant germ cell tumours (GCTs) of the testis are rare neoplasms, but the most common solid malignancies in young men. World Health Organization guidelines divide GCTs into five types, for which numerous immunohistochemical markers allow exact histological subtyping in the majority of cases. In contrast, a germ cell origin is often hard to prove in metastatic GCTs that have developed so-called somatic malignant transformation. A high percentage, up to 89%, of GCTs are characterised by the appearance of isochromosome 12p [i(12p)]. Fluorescence in-situ hybridisation has been the most common diagnostic method for the detection of i(12p) so far, but has the disadvantages of being time-consuming, demanding, and not being a stand-alone method. The aim of the present study was to establish a quantitative real-time polymerase chain reaction assay as an independent method for detecting i(12p) and regional amplifications of the short arm of chromosome 12 by using DNA extracted from formalin-fixed paraffin-embedded tissue.

METHODS AND RESULTS

A cut-off value to distinguish between the presence and absence of i(12p) was established in a control set consisting of 36 tumour-free samples. In a training set of 149 GCT samples, i(12p) was detectable in 133 tumours (89%), but not in 16 tumours (11%). In a test set containing 27 primary and metastatic GCTs, all 16 tumours with metastatic spread and/or somatic malignant transformation were successfully identified by the detection of i(12p).

CONCLUSION

In summary, the qPCR assay presented here can help to identify, further characterise and assign a large proportion of histologically inconclusive malignancies to a GCT origin.

Extraovarian dysgerminoma in a pregnant woman: an extremely rare finding

Extraovarian germ cell tumors are very rare and their occurrence during pregnancy is exceptional. In this case report an abdominal mass was shown by ultrasonography, during a routine monitoring of a 26-year-old pregnant woman. The patient was left under radiological control in the following months in order to bring the pregnancy to term. A few months after the delivery, the patient underwent surgery and a diagnosis of extraovarian (abdominal) dysgerminoma was made. To the best of our knowledge, there are only 3 other case reports describing an extra-gonadal dysgerminoma occurring during pregnancy. The aim of this study was to report an extremely rare tumor, whose management can be challenging first because this neoplasm has some differences from its ovarian and testicular counterparts. Furthermore, the occurrence during pregnancy makes the multidisciplinary approach mandatory since 3 distinct but not independent entities are involved (tumor, mother and fetus).

Comprehensive genetic analysis of pediatric germ cell tumors identifies potential drug targets

To elucidate the molecular pathogenesis of pediatric germ cell tumors (GCTs), we performed DNA methylation array analysis, whole transcriptome sequencing, targeted capture sequencing, and single-nucleotide polymorphism array analysis using 51 GCT samples (25 female, 26 male), including 6 germinomas, 2 embryonal carcinomas, 4 immature teratomas, 3 mature teratomas, 30 yolk sac tumors, and 6 mixed germ cell tumors. Among the 51 samples, 11 were from infants, 23 were from young children, and 17 were from those aged ≥10 years. Sixteen of the 51 samples developed in the extragonadal regions. Germinomas showed upregulation of pluripotent genes and global hypomethylation. Pluripotent genes were also highly expressed in embryonal carcinomas. These genes may play essential roles in embryonal carcinomas given that their binding sites are hypomethylated. Yolk sac tumors exhibited overexpression of endodermal genes, such as GATA6 and FOXA2, the binding sites of which were hypomethylated. Interestingly, infant yolk sac tumors had different DNA methylation patterns from those observed in older children. Teratomas had higher expression of ectodermal genes, suggesting a tridermal nature. Based on our results, we suggest that KIT, TNFRSF8, and ERBB4 may be suitable targets for the treatment of germinoma, embryonal carcinomas, and yolk sac tumors, respectively.

Yasuo Kubota et al. report a multi-omic analysis of pediatric germ cell tumors from 51 patients ranging in age from 2 months to 19 years. They identify unique methylation, expression, and mutational patterns for each of the main subtypes and propose potential target genes for treatments against the three main subtypes.