Spontaneous radiographic resolution of malignant and benign cysts.

Two rare cases of cystic lesions with spontaneous radiographic resolution are presented. One is a 21-year-old man with a mediastinal seminoma containing a cystic lesion within the neoplasm that disappeared spontaneously on subsequent chest radiography and computed tomography. Another is a 65-year-old man with a pericardial cyst that also disappeared in subsequent chest radiography. The possible mechanisms for such rare occurrences are discussed.