DNA variants in teratomatous and embryonal components of primary mediastinal nonseminomatous germ cell tumor: a case report and literature review

Introduction: Primary germ cell tumors (GCTs) are highly malignant and often affect young adult men. They commonly occur in the reproductive organs but can also affect structures along the body’s midline, including the mediastinum, retroperitoneum, and pineal gland. Methods: We present the genetic analyses of a 21-year-old African American man diagnosed with primary GCT of the anterior mediastinum. Results: DNA variants of NRAS and TP53 were identified in the teratomatous and embryonic components of his tumor. These variants were not identified in benign tissue, indicating their somatic origin. Several copy number variants were detected in both tumor components, including gains of chromosome 1, 3p, 12p with loss of homozygosity, and 21; segmental loss of 9q; and 13q copy neutral loss of homozygosity. Divergent copy number variants were identified in either teratomatous or embryonic components, including gains of chromosomes 7, 9, and 17 in the teratomatous component and gains of chromosomes 2, 4, 6, 8, and 11 in the embryonic component. Discussion: These DNA alterations may be genetic drivers of tumor initiation or progression in our patient. They may have diagnostic and prognostic value for mediastinal GCTs.