Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 2, 2011, pp. 315-316

Neurology India, Vol. 59, No. 2, March-April, 2011, pp. 315-316

Neuroimage

Completely calcified lumbar synovial cyst

Manish K Kasliwal, Harel Deutsch

Department of Neurosurgery, RUSH University Medical Center, Chicago, IL, USA

Correspondence Address: Manish K Kasliwal, Department of Neurosurgery, Suite 1115, RUSH University Medical Center, Chicago, IL 60612, USA, manish_kasliwal@rush.edu

Code Number: ni11093

PMID: 21483152

DOI: 10.4103/0028-3886.79173

A 56-year-old woman presented with back pain of 3 years duration and magnetic resonance imaging (MRI) of spine done at the onset of symptoms showed degenerative changes in the lumbosacral spine [Figure - 1]. A repeat MRI of lumbosacral spine performed for the recent worsening of symptoms, and development of right lumbar radiculopathy, showed a space occupying lesion, iso-hypointense lesion on T1W and hypointense on T2W image sequences with no obvious contrast enhancement. In addition, there were degenerative changes of the spine [Figure - 2]. Computed tomography (CT) scan of the lumbosacral spine revealed a 1.5 Χ 1.5 rounded well-delineated completely calcified lesion abutting the right L4−5 facet joint with facet arthropathy [Figure - 3]. A diagnosis of a completely calcified degenerative synovial cyst was made and surgical excision of the same with L4−5 fusion was performed.

Synovial cysts possibly develop due to degenerative changes in the spine; most common pathogenesis being osteoarthritis of facet joint, degenerative spondylosis and/or spondylolisthesis with resulting weakening of the joint capsule and resultant cyst formation. ^[1] These can be asymptomatic or may present with back pain or radiculopathy. Moreover, the development of synovial cyst superimposed on symptomatic degenerative spine disease can result in development of radicular symptoms. The imaging appearance on MRI facilitates the preoperative diagnosis more than 90% of times and is considered the investigative modality of choice. ^[2] Hypointensity on T1W and hyperintensity on T2W images is quite characteristic of synovial cyst. ^[1],[2] Factors affecting variability of the MR appearance include proteinaceous concentration of the fluid, presence or absence of blood, calcification, and gas (vacuum phenomenon) in the spinal canal. ^[1] CT is of value in illustrating indirect findings such as marginal calcifications, gas formation, or bone erosion of the adjacent lamina. ^[3] Though calcification can occur in synovial cyst; marginal calcification remains most common giving rise to characteristic hypointense rim on T2W MRI. ^[1],[2] A completely calcified synovial cyst is very rare and can be deceptive on MR imaging due to total signal loss as happened in the present case showing as hypointense mass on T1 and T2 weighted images which can be very well appreciated on a CT. ^[4] Completely calcified synovial cyst can be misdiagnosed as spinal bony tumor, tumor calcinosis, or calcified ligamentum flavum. ^[5] The presence of degenerative changes in the spine especially in the adjacent facet can help diagnosing the lesion as synovial cyst. Treatment options for spinal synovial cysts can be nonsurgical or surgical. ^[6] Considering the rarity of spontaneous resolution and poor outcomes with other conservative measures, there has been a reasonable agreement on the need of surgery for symptomatic synovial cysts; ^[4],[6] the extent of surgery and the need of concomitant fusion remain controversial, however.

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