Misleading Density of Mediastinal Cysts on Computerized Tomography

Five patients seen with roentgenographic evidence of smooth, rounded mediastinal masses were evaluated by computerized tomographic (CT) scanning. Density readings from the lesion were interpreted in all patients as being equivalent to solid tissue. With these findings, thoracotomy seemed necessary for definitive diagnosis. All 5 lesions were found to be thin-walled cystic structures containing thick viscid fluid. Contrary to views expressed in the radiology literature, we conclude that computerized tomography does not differentiate reliably between solid and cystic mediastinal masses.