Bronchogenic cysts in the adult: diagnostic criteria derived from the correct use of standard radiography and computed tomography

PURPOSE: This study was undertaken to identify the radiographic and computed tomography patterns allowing a diagnosis of bronchogenic cyst. MATERIALS AND METHODS: We retrospectively reviewed chest radiographs and CT scans of 21 adults (ten men and 11 women, age range 18-74 years) with a histologically confirmed diagnosis of bronchogenic cyst. RESULTS: Sixteen cysts were located in the mediastinum and five in the lungs. On chest radiography, mediastinal cysts appeared as sharply marginated rounded areas of increased opacity; intrapulmonary cysts also exhibited an air-fluid interface. CT confirmed these morphological features in all cases. In addition, analysis of attenuation values allowed the subdivision of mediastinal cysts into three groups: fluid density (four cases), air density (two cases) and soft-tissue density (ten cases). CONCLUSIONS: All bronchogenic cysts were visualised on chest radiography, but the findings were nonspecific and required further characterisation by CT. The CT findings proved to be diagnostic when cystic attenuation values were evident. When soft-tissue attenuation values were demonstrated, a confident diagnosis was not possible, and other solid lesions had to be considered. In such cases, magnetic resonance imaging may be helpful to ascertain the cystic nature of the lesions.