[Computed tomography diagnosis of clinically well-tolerated bilateral lumbar vertebral synovial cysts].

We report two very rare cases of bilateral synovial cyst of the lumbar spine arising at the L4-L5 level. The diagnosis was made by CT without any ambiguity. The reported lesions illustrate almost the complete panel of CT findings in synovial cyst of the spine including gas formation, marginal calcifications, bone erosion of the adjacent lamina, and in one case the original development of an intracystic calcified nodule. The symptoms of the two patients improved with medical treatment only and spontaneous regression of the calcified cysts was confirmed in one case.