This article describes two case studies involving lumbar facet joint synovial cyst causing acute sciatica and progressive neurological deficit. The cases involve women, 57 and 69 years old, respectively. The first patient was presented with left buttock and lower leg pain, numbness and paresthesia, while the second one had progressive right lower leg pain for 3 months. Magnetic resonance imaging revealed a high intensity cystic lesion arising from the facet joint, subsequently causing spinal stenosis and exiting nerve root compression. Surgery was performed, including laminectomy and cyst excision. Microscopic observation confirmed synovial cysts. Following operation, clinical symptoms of the patients improved significantly with no neurological sequelae. Based on our experience with these two patients treated by open surgery in our hospital, this study attempted to more thoroughly elucidate the significance and treatment outcome of a surgically treated lumbar synovial cyst. Moreover, relevant literature was reviewed, with a focus on their clinical presentations, imaging findings, and postoperative surgical outcomes.