What is the prevalence of tumors of the mediastinum?

Updated: Feb 16, 2021
  • Author: Mary C Mancini, MD, PhD, MMM; Chief Editor: John Geibel, MD, MSc, DSc, AGAF  more...
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Answer

A review of collected series reveals that many mediastinal neoplasms and masses vary in incidence and presentation depending on patient age. Also, a number of mediastinal tumors characteristically occur in specific areas within the mediastinum. [14, 15]

Historically, in adults the most common type of mediastinal tumor or cyst found is the neurogenic tumor, followed by thymic tumors, lymphomas, and germ cell tumors. Foregut and pericardial cysts are the next most frequently occurring abnormality within this group. However, more recent data from several large series indicate that thymomas have become the most common mediastinal tumor. Some series also indicate that mediastinal lymphoma has also passed neurogenic tumors in frequency.

In children and infants, neurogenic tumors are also the most commonly occurring tumor or cyst, followed by foregut cysts, germ cell tumors, lymphomas, lymphangiomas, angiomas, tumors of the thymus, and pericardial cysts.

In patients younger than 20 years or older than 40 years, approximately one third of mediastinal tumors are malignant, whereas in patients aged 20-40 years, roughly half are malignant.

Approximately two thirds of mediastinal tumors and cysts are symptomatic in the pediatric population, while only approximately one third produce symptoms in adults. The higher incidence of symptoms in the pediatric population is most likely related to the fact that a mediastinal mass, even a small one, is more likely to have a compressive effect on the small flexible airway structures of a child.

When considering all age groups, nearly 55% of patients with benign mediastinal masses are asymptomatic at presentation, compared to only approximately 15% of those in whom masses are found to be malignant.

Although lymphomas can be found in any of the mediastinal compartments, many of them manifest in the anterior compartment. [16] As many as 45% of masses found in the anterior mediastinum of children are lymphomas, and, in adults, they are the second most common anterior mediastinal mass. [17]

True ectopic thyroid tissue, entirely detached from the cervical thyroid gland and having its own (albeit anomalous) blood supply in the mediastinum, is extremely rare. Only a few case reports exist. Most thyroid tissue found in the mediastinum results from an extension of the cervical thyroid gland, usually as a goiter. More than 80% of these extensions lie beneath the manubrium and in a position superior to the arch vessels. The remainder can lie within the middle mediastinum, some in a retrotracheal or even retroesophageal position. [18]

According to various reports, occult malignancy, usually papillary thyroid carcinoma, can be found in resected intrathoracic thyroid tissue. This has been reported in approximately 5% of cases.

Of all parathyroid tumors, only 1-3% are truly mediastinal in location, defined as those inaccessible by standard cervical exploration and requiring median sternotomy for excision. [13]

Mesenchymal tumors represent approximately 6% of all masses found in the mediastinum. [19, 11] More than 50% of these are malignant.


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