Synovial cyst is a relative disease. We report a synovial cyst with literature. The cyst reduced remarkably after arthrography. A 45-year-old woman had been suffering back pain and left leg pain for seven months, and was unable to stand or walk. MRI indicated a tumor in the left side between L5 and S1, and arthrography was performed to remove the synovial cysts. After arthrography, pain of the left leg reduced remarkably and the cystic component was found to have disappeared in MRI. No lumbar pain nor left leg pain recurred. Way of curing synovial cysts include resting, use of instruments, steroid injection, and operation to remove a part of the vertebral arch, and removal of the synovial cysts. In this case, the wall of the cysts broke when the needle of the arthrography was injected, and the components of the cyst leaked out. In the removal of synovial cysts, arthrography is sometimes useful for diagnosis and curing.
