Mixed germ cell tumor of the mediastinum

Last revised by Joachim Feger on 27 Dec 2021

Mixed germ cell tumors of the mediastinum or mediastinal mixed germ cell tumors are malignant non-seminomatous germ cell tumors of the mediastinum consisting of more than one type of germ cell tumor.

The term ‘malignant teratoma’ is not recommended.

Mixed germ cell tumors of the mediastinum are rare and are almost always seen in men 1. In adults, the two most common tumor elements are teratoma and embryonal carcinoma, whereas in children yolk sac and teratomatous components are more commonly seen 1.

Klinefelter syndrome

The final diagnosis is based on histology and requires the presence of more than one type of germ cell tumor 1.

Clinical signs and symptoms include chest-related symptoms such as dyspnea, chest pain, cough, and superior vena cava syndrome like in other mediastinal germ cell tumors. Similarly, there will be an elevation of serum tumor markers 1,2.

Mediastinal choriocarcinomas might cause the following complications ref:

Mixed germ cell tumors are characterized by different types of germ cell tumors e.g. seminomatous and teratomatous components 1.

Mixed germ cell tumors in adults frequently feature chromosomal amplifications or isochromosome 12p.

Children lack the 12p gains but often have additions in the 1q, 3 and 20q locations as well as losses at 1p, 4q and 6q. Patients with Klinefelter syndrome have additional copies of the X-chromosome 1.

Primary mediastinal mixed germ cell tumors are usually found in the anterior mediastinum 1.

Mixed germ cell tumors are heterogeneous with a solid fleshy gross appearance with intermingled areas of hemorrhage and necrosis and variably cystic or fatty components 1.

Microscopically mediastinal mixed germ cell tumors are characterized by the different morphologies of pure germ cells in any combination 1.

On imaging studies mixed germ cell tumors are heterogeneous masses with areas of hemorrhage and necrosis.

Cystic spaces and adipose tissue indicate teratomatous components.

Chest x-rays might show widening of the anterior mediastinum 2,3.

Mixed germ cell tumors have a heterogeneous appearance with signs of hemorrhage and necrosis as well as variably cystic and/or fatty components 2-4. CT might reveal infiltration of adjacent structures, including superior vena cava compression, pleural or pericardial effusions, and distant metastases 3.

MRI reports of mixed germ cell tumors are scarce. They have been described as large heterogeneous masses 4.

MRI can assess fatty and cystic components 4.

The radiological report should include a description of the following:

  • location and extent of the tumor
  • relation to the heart and great vessels
  • infiltration and/or compression of adjacent structures
    • superior vena cava obstruction
    • pleural effusion
    • pericardial effusion
  • nodal disease
  • distant metastases

Management includes chemotherapy with subsequent surgical resection. Prognosis is not good with a 5-year overall survival of about 45% 1. Patients younger than 30 years and children have a better prognosis. Localized disease and normal hCG levels are also favorable 1.

Condition or tumors that might mimic the appearance of  tumors  include 1:

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Cases and figures

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