Mediastinal germ cell tumor
Encyclopedia
Malignant
Malignant
Malignancy is the tendency of a medical condition, especially tumors, to become progressively worse and to potentially result in death. Malignancy in cancers is characterized by anaplasia, invasiveness, and metastasis...

 mediastinal germ cell tumors of various histologies were first described as a clinical entity approximately 50 years ago. Mediastinal
Mediastinum
The mediastinum is a non-delineated group of structures in the thorax, surrounded by loose connective tissue. It is the central compartment of the thoracic cavity...

 and other extragonadal germ cell tumors were initially thought to represent isolated metastases
Metastasis
Metastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...

 from an inapparent gonadal primary site.

Etiology

Some investigators suggest that this distribution arises as a consequence of abnormal migration of germ cells during embryogenesis
Embryogenesis
Embryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote...

. Others hypothesize a widespread distribution of germ cells to multiple sites during normal embryogenesis, with these cells conveying genetic information or providing regulatory functions at somatic sites.

Epidemiology

Malignant germ cell tumors of the mediastinum are uncommon, representing only 3 to 10% of tumors originating in the mediastinum. They are much less common than germ cell tumors arising in the testes, and account for only 1 to 5% of all germ cell neoplasms.

Clinical Characteristics

Unlike benign germ cell tumors of the mediastinum, malignant mediastinal tumors are usually symptomatic at the time of diagnosis. Most mediastinal malignant tumors are large and cause symptoms by compressing or invading adjacent structures, including the lungs, pleura, pericardium, and chest wall.

Seminomas grow relatively slowly and can become very large before causing symptoms. Tumors 20 to 30 cm in diameter can exist with minimal symptomatology.

Evaluation and Staging

The diagnosis of a mediastinal germ cell tumor should be considered in all young males with a mediastinal mass. In addition to physical examination and routine laboratory studies, initial evaluation should include CT of the chest and abdomen, and determination of serum levels of HCG and alpha-fetoprotein.

Treatment

Pure mediastinal seminomas are curable in the large majority of patients, even when metastatic at the time of diagnosis. These tumors are highly sensitive to radiation therapy
Radiation therapy
Radiation therapy , radiation oncology, or radiotherapy , sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.Radiation therapy is commonly applied to the cancerous tumor because of its ability to control...

 and to combination chemotherapy
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....

. However, the cardiotoxicity of mediastinal radaition is substantial and the standard treatment of mediastinal seminomas is with chemotherapy using bleomycin, etoposide and cisplatin for either three or four 21-day treatment cycles depending on the location of any metastatic disease.

In summary, most patients with mediastinal seminoma can be cured with chemotherapy, and all patients should be approached with this intent. Patients with small tumors (usually asymptomatic) that appear resectable should undergo thoracotomy and attempted complete resection followed by chemotherapy.

The treatment for mediastinal nonseminomatous germ cell tumors should follow guidelines for poor-prognosis testicular cancer. Initial treatment with four courses of bleomycin, etoposide, and cisplatin, followed by surgical resection of any residual disease, is considered standard therapy.

Sources


See also

  • Mediastinitis
    Mediastinitis
    Mediastinitis is inflammation of the tissues in the mid-chest, or mediastinum. It can be either acute or chronic.Acute mediastinitis is usually bacterial and due to rupture of organs in the mediastinum. As the infection can progress rapidly, this is considered a serious condition...

  • Mediastinal fibrosis
    Mediastinal fibrosis
    Mediastinal fibrosis is a rare late complication of histoplasmosis. It is characterized by invasive, calcified fibrosis centered on lymph nodes that block major vessels and airways....

  • Mediastinum
    Mediastinum
    The mediastinum is a non-delineated group of structures in the thorax, surrounded by loose connective tissue. It is the central compartment of the thoracic cavity...

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