Mediastinal tumors
Mediastinal tumors are abnormal growths located in the mediastinum, the central cavity of the chest that contains vital structures such as the heart, esophagus, and trachea. These tumors can be benign or malignant and are categorized based on their location: anterior, middle, or posterior mediastinum. Common types include thymomas, lymphomas, teratomas, and neurogenic tumors, with specific risk factors associated with certain genetic conditions. Symptoms may vary widely, with many individuals experiencing no symptoms at all; when present, symptoms can include cough, chest pain, and difficulty swallowing.
Diagnosing mediastinal tumors typically involves imaging techniques like chest X-rays, CT scans, and MRIs, often complemented by biopsies for definitive diagnosis. Treatment approaches depend on the type of tumor and may involve surgery, chemotherapy, or radiation therapy. The prognosis is largely determined by the tumor type, with some having favorable outcomes if treated promptly, while others, like certain mesenchymal tumors, may present significant challenges. Understanding these tumors is crucial for early detection and effective management, highlighting the importance of medical consultation and timely interventions.
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Mediastinal tumors
Also known as: Mediastinal neoplasias
Related conditions: Pericardial cysts, ectopic thyroid, bronchiogenic cysts
Definition: Mediastinal tumors are benign or malignant growths in the mediastinum, which is the central chest cavity that separates the lungs and contains the heart, aorta, esophagus, thymus, and trachea.
Risk factors: Risk factors include neurofibromatosis (von Recklinghausen disease), Li-Fraumeni syndrome, and a family history of Hodgkin disease.
Etiology and the disease process: The mediastinum is divided into the front, middle, and posterior mediastinum. The anterior mediastinum lies between the heart and the sternum. The middle mediastinum extends from the surface of the heart to the trachea (windpipe), and the posterior mediastinum begins behind the trachea and ends at the front of the vertebral column (backbone). Each mediastinal compartment is subject to specific types of tumors.
Anterior mediastinal tumors include tumors of the thymus (thymomas), lymphomas, teratomas, and thyroid tumors. Thymomas usually occur in adults, but 15 percent of them occur in children. Lymphomas account for 10 to 20 percent of anterior mediastinal tumors. Hodgkin disease causes most adult cases of mediastinal lymphomas. Teratomas (germ-cell tumors) account for 10 to 15 percent of mediastinal tumors. Thyroid tumors grow from goiters and primarily occur in women.
Tumors of the middle mediastinum include lymphomas (most common), mesenchymal tumors, and carcinomas. Mesenchymal tumors account for 6 percent of primary mediastinal tumors and are also called soft-tissue tumors that originate in connective tissue within the chest (about half are malignant).
Neurogenic tumors (derived from nerve cells) are the most common tumors of the posterior mediastinum and include malignant schwannomas and neuroblastomas. Some 19 to 39 percent of mediastinal tumors are neurogenic and are usually benign in adults but malignant in children. Endocrine and mesenchymal tumors are also found in the posterior mediastinum.
Though typically diagnosed in people between the ages of thirty and fifty, mediastinal tumors can occur at any age and in any tissue that passes through the chest.
Incidence: Thymomas occur at a rate of 3 cases per million people per year. Lymphoblastic lymphomas in children occur at a rate of 6 cases per million. There are about 6 cases of mediastinal germ-cell tumors per million in children per year. Some 125 children per year in the United States are diagnosed with mediastinal neuroblastomas.
Symptoms: Half of mediastinal tumors produce no symptoms, but masses in the chest can compress other tissues and prevent proper functioning. The most common symptoms are cough, shortness of breath, and chest pain. Accompanying symptoms include trouble swallowing (dysphagia), chest pain, fever, chills, night sweats, coughing up blood (hemoptysis), hoarseness, unintentional weight loss, wheezing, tender or swollen lymph nodes (lymphadenopathy), and stridor (high-pitched, noisy respiration).
Between 35 and 50 percent of people with thymomas experience myasthenia gravis–like symptoms that include weakness of eye muscles, drooping of one or both eyelids (ptosis), and fatigue. Certain mediastinal tumors can produce neurotransmitters (catecholamines) that significantly raise blood pressure (hypertension). Other types of neurosarcomas can make insulinlike substances that can cause low blood sugar concentrations (hypoglycemia).
Blood work may show abnormally high levels of serum calcium (hypercalcemia) and abnormally low levels of antibodies (hypogammaglobulinemia), circulating blood cells (cytopenia), and normal red blood cells (pernicious anemia).
Screening and staging: Many different types of imaging tests can detect mediastinal tumors. Chest x-rays are essential to determine the location of mediastinal tumors. Computed tomography (CT) and magnetic resonance imaging (MRI) scans are common imaging methods for detecting mediastinal masses. CT scans are also used to direct needle biopsies of potentially tumorous masses. Positron emission tomography (PET) scans are used to determine the spread of the tumor to other parts of the body. If the tumor is located in a difficult-to-reach spot, then laparoscopic surgery called mediastinoscopy is used to biopsy the mass.
Most mediastinal tumors are solid tumors, which are graded by TNM (tumor/lymph node/metastasis) staging. T refers to the primary tumor and grades it from 0 to 4. N specifies the spread of the cancer to nearby lymph nodes (ranked 0 to 3). M represents metastasis or spread of the tumor beyond the lymph nodes to other parts of the body (0 or 1).
Treatment and therapy: Thymomas are primarily treated with surgery, followed by radiation or chemotherapy. For lymphomas, chemotherapy followed by radiation is the treatment of choice. For neurogenic tumors, surgery is the treatment of choice. It is possible to surgically resection some mesenchymal tumors, and radiation can help in some cases, but some fibrosarcomas are not treatable with surgery or chemotherapy. Malignant schwannomas are very aggressive tumors that require multiagent chemotherapy.
Prognosis, prevention, and outcomes: The outcome is highly dependent on the type of tumor. If untreated, the prognosis is very poor. If properly treated, the prognosis for thymomas, lymphomas, thyroid tumors, teratomas, and some neurogenic tumors is generally quite good. Mesenchymal tumors tend to have a poor prognosis.
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