Chest ImagingMediastinal lipomatosis
accumulation of excess unencapsulated fat within the
mediastinum. This
benign condition, usually seen in adult patients, may be part of generalized obesity, but not exclusively. It may be seen in patients with Cushing's disease or those treated with steroid therapy. The usual appearance on the chest radiograph is a smooth widening of the anterior and superior
mediastinum without any deformity of the trachea. The fat pads in the costophrenic angles are also often enlarged. Excess fat within the paravertebral region may result in bilateral lateral displacement of the paraspinal lines. The definite diagnosis of
mediastinal lipomatosis may be made at
CT. Fat is recognized on
CT scans by its low attenuation, which varies from -70 -130 Hounsfield units (
Fig.1). On MR scans, fat demonstrates high signal intensity on T1-weighted images. Using a fat suppression sequence, the signal intensity of fat decreases, permitting a distinction from other tissues with a bright
T1 signal. Homogeneity of fat and absence of compression of surrounding structures differentiate this
benign condition from multiple
thoracic lipomas.
PG
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CT scan showing a mediastinal lipomatosis in an asymptomatic patient, depicted by an increase of the mediastinal width on a PA chest radiograph.
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Mediastinal lipomatosis, Fig.1 | |