[A case report; ganglion cyst of a cervical facet joint].

: Ganglion or synovial cyst typically occurs in peripheral joints and tendon sheaths such as elbow joint or wrist joint, but rarely in the spinal facet joint. From reported cases the most common site involved seems to be the lumbar facet joint. Only three cases of cervical ganglion or synovial cyst have so far been found in the literature. A case of cervical ganglion cyst was reported. The patient was a 2-year-old boy who was found to have a tumor in the midline of the nape. He had no history of trauma. Neurological and physical examination revealed no abnormalities. On CT scan a round low dense lesion with clear margin was found in the nape. Enhanced CT scan showed ring-like enhancement. Magnetic resonance (MR) imaging showed a well defined lesion of high intensity on T1- and T2-weighted images. At operation, the lesion was found to form a cyst containing old hematoma, and the cyst wall seemed to be fixed to the cervical spinal facet joint. The tumor was histologically diagnosed as ganglion cyst.