SUMMARY OF BACKGROUND DATA. Case studies documenting the incidence of thoracic intraspinal, extradural synovial cysts are limited. The occurrence of synovial cysts is associated with varied symptoms that differ among cervical, thoracic, and lumbar regions. The clinical appearance may be similar to other spinal diseases. METHODS. This report describes symptoms exhibited by and care provided for a patient with extradural synovial thoracic cyst.