CT diagnosis of benign mediastinal abnormalities.

Thoracic CT scanning was performed in 49 adult male patients to evaluate a suspected mediastinal mass. A correct diagnosis would have been made in only 20 instances on the basis of conventional chest radiography. Specific diagnoses established by CT included 14 cases of local or diffuse mediastinal fat deposition, five mediastinal cysts, and six anomalies or aneurysms of the great vessels. Four miscellaneous lesions were also clarified. Thoracic angiography would undoubtedly have diagnosed vascular abnormalities, but was obviated in most instances. CT accurately defined anatomic relationships and distinguished vascular from nonvascular masses in the 16 patients who underwent diagnostic thoracotomy or mediastinoscopy. When CT demonstrated a fatty or cystic lesion, no attempt at tissue confirmation was undertaken in all but two of the asymptomatic patients. Clinical follow-up from 6 months to 3 years in conjunction with select correlative radiologic procedures have supported the CT findings in the nonoperated group. CT should be the initial procedure for evaluating most patients with mediastinal abnormalities detected by plain chest radiography. If the patient is asymptomatic and the information provided by CT indicates a benign process, conservative management with careful follow-up is justified.