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The mediastinum is the located in the thoracic cavity between the lungs, and it includes the heart, aorta, thymus gland, trachea and esophagus. When a chest X-ray is taken, the cavity might appear wider than it should. A widened mediastinum can be caused by image distortion from when the X-ray was taken. Other causes can be serious medical issues such as aortic dissection, mediastinal tumors and descending necrotizing mediastinitis.
Chest X-rays can indicate a widened mediastinum without the area truly being enlarged. Sometimes, chest X-rays are ordered for reasons other than possible mediastinum problems. To capture images of certain areas in the chest, a patient might need to be arranged in a position that can make the mediastinum appear to be widened. By taking into consideration why the patient had the X-rays done and how many films were taken, a radiologist should be able to determine whether the condition is a medical concern or an X-ray glitch.
The widening of the mediastinum can be caused by serious medical conditions, such as an aorta dissection. The aorta is a major artery made up of three layers. An aorta dissection happens when the innermost layer, where the blood flows, tears and allows the blood to enter the other layers. This causes the aorta to bulge and potentially to rupture. A widened mediastinum usually is found during an aortography, a procedure in which contrast dye is injected into the patient’s bloodstream before a chest X-ray is performed.
Symptoms of an aorta dissection might mimic those of a heart attack, which can include sudden radiating chest pain. Other signs could be profuse sweating and different pulse rates in the arms. Medical attention should be sought if any of these symptoms occur.
Mediastinal tumors, such as germ cell, lymphoma, thymic cyst and goiters, can also show a widened mediastinum on a chest X-ray. These tumors can be either cancerous or benign. Many people who have a mediastinal tumor might not have any symptoms. If symptoms do occur, it usually is because the tumor is pressing against something. A person who has a mediastinal tumor might experience night sweats, wheezing and shortness of breath.
A rare but potentially fatal condition called descending necrotizing mediastinitis can also cause a widened mediastinum. This condition is caused by the spreading of a head or neck infection to the mediastinum. Tonsillitis, dental abscess and sinusitis can potentially cause descending necrotizing mediastinitis if the infection is not treated. Symptoms include a sore or swollen neck from the spreading infection, fever and shortness of breath. This can be a life-threatening condition, and medical attention should be sought as soon as possible.
As uncomfortable as getting an x-ray can be, I'd much rather be called back for a second session than rely on the diagnosis of a widened mediastinum based on the first set of x-rays alone. Those other causes sound so serious that I'd be hoping for an x-ray positioning error the entire time.