SDHx and Non-Chromaffin Tumors: A Mediastinal Germ Cell Tumor Occurring in a Young Man with Germline SDHB Mutation

Germline susceptibility from broad genomic profiling of pediatric brain cancers

Background

Identifying germline predisposition in CNS malignancies is of increasing clinical importance, as it contributes to diagnosis and prognosis, and determines aspects of treatment. The inclusion of germline testing has historically been limited due to challenges surrounding access to genetic counseling, complexity in acquiring a germline comparator specimen, concerns about the impact of findings, or cost considerations. These limitations were further defined by the breadth and scope of clinical testing to precisely identify complex variants as well as concerns regarding the clinical interpretation of variants including those of uncertain significance.

Methods

In the course of conducting an IRB-approved protocol that performed genomic, transcriptomic and methylation-based characterization of pediatric CNS malignancies, we cataloged germline predisposition to cancer based on paired exome capture sequencing, coupled with computational analyses to identify variants in known cancer predisposition genes and interpret them relative to established clinical guidelines.

Results

In certain cases, these findings refined diagnosis or prognosis or provided important information for treatment planning.

Conclusions

We outline our aggregate findings on cancer predisposition within this cohort which identified 16% of individuals (27 of 168) harboring a variant predicting cancer susceptibility and contextualize the impact of these results in terms of treatment-related aspects of precision oncology.

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.

A Novel Germline SDHA Gene Mutation and Co-Occurring Somatic KIT Activating Mutation in a Patient With Pediatric Central Nervous System Germ Cell Tumor: Case Report

Central nervous system germ cell tumors (CNS GCTs) are a heterogeneous group of primary CNS tumors. GCTs are more common and mostly observed in pediatric and young adult patients. CNS GCTs are divided into germinomas and non-germinomatous germ cell tumors (NGGCTs), with different therapeutic strategies depending on diagnosis. Herein, we report a patient with pediatric central nervous system germinoma harboring a somatic KIT p.Y823D and a heterozygous germline SDHA p. T396Nfs*14 mutation detected by next generation sequencing. After surgery, the patient received chemotherapy (temozolomide + nedaplatin + etoposide). This is the first report of a Chinese pediatric patient with CNS GCT harboring concurrent germline SDHA and somatic KIT mutation, which enriches molecular profiles of CNS GCTs and provides more molecular evidence of clinical diagnosis and potential targeted therapy in CNS GCTs.

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.