Mediastinitis is inflammation of the mediastinum (the chest cavity, which contains the heart, the thymus gland, some lymph nodes, and parts of the esophagus, aorta, thyroid, and parathyroid glands—see Overview of Pleural and Mediastinal Disorders).
Mediastinitis may be
Mediastinitis most often results from an infection. The two most common causes of infection are
The esophagus may be torn accidentally during a procedure such as endoscopy, by forceful vomiting, or by an injury to the chest. Sometimes a tear results from swallowing a caustic substance such as a lye or certain button batteries.
Median sternotomy involves an incision made down the length of the breastbone (sternum), splitting it in two. Median sternotomy is used so doctors can gain access to the chest for procedures such as heart transplantation, heart valve surgery, or coronary artery bypass surgery.
Less common causes include tuberculosis, histoplasmosis (a fungal infection), sarcoidosis, radiation therapy, or silicosis. These disorders tend to cause chronic mediastinitis. Chronic mediastinitis may result in fibrosing mediastinitis. In fibrosing mediastinitis, blood vessels or airways (bronchi) may become blocked.
An esophageal tear causes sudden, severe chest pain and shortness of breath. Some people have symptoms of infection such as fever and chills.
If mediastinitis develops after chest surgery, people may have drainage from the incision site. People who have chronic fibrosing mediastinitis may gradually become short of breath.
Doctors can often make the diagnosis based on the symptoms if people have a condition that can cause mediastinitis—for example, if people have symptoms that suggest mediastinitis and have recently had a procedure involving the chest or the esophagus or have tuberculosis or another slowly developing infection.
When mediastinitis develops suddenly, symptoms are usually severe enough that doctors suspect it in people who cannot report possible causes, such as those who are intoxicated and do not remember vomiting forcefully or young children who may have swallowed a caustic substance.
The diagnosis is confirmed by a chest x-ray or CT.
When mediastinitis occurs in a person who has had median sternotomy, doctors may insert a needle into the chest through the breastbone and remove fluid for examination under a microscope (aspiration biopsy).