MyPACS.net: Radiology Teaching Files > Case 10056848

previously visited SYNOVIAL CYST OF THE LUMBAR SPINE
Contributed by: Fritsch & Thompson, Radiologist, Diagnostic Radiology of Houston, Texas, USA.
Patient: 52 year old female
History:

Low back pain with radiating left leg pain. 

Clinical exam revealed decreased patellar reflex and hypesthesia of a L4 dermatomal pattern.

Images:[small]larger

Fig. 1: Lateral lumbar spine radiograph.

Fig. 2: Lateral spot lumbar spine radiograph.

Fig. 3: AP lumbar spine radiograph.

Fig. 4: AP spot lumbar spine radiograph.

Fig. 5: Sagittal T1 (left) and sagittal T2 Fat Sat (right). Note posterior hypointense T1 and hyperintense T2 extradural mass compressing on traversing nerve roots. This mass does not communicate with the degenerated L3-L4 disc.

Fig. 6: Axial T2 image at L3-L4 level. Note the orange reference line on the sagittal T2 image on right. There is a posterior hyperintense mass projecting from the left facet joint (click annotation button).

Fig. 7: Second axial T2 image at L3-L4 level. Note the orange reference line on the sagittal T2 image on right. There is a posterior hyperintense mass projecting from the left facet joint. Also note the curvilinear high intensity change of the anulus fibrosis posterolateral margin. This is consistent with a concentric tear or fissure. (click annotation button).
Findings:

X-rays:
Mild degenerative changes with decreased disc space at L3-L4.

MRI:
L3-L4:
There is signal loss nucleus pulposus with mild loss of disc height. A concentric 12 mm annular tear is identified in the left posterolateral margin (4 o’clock to 5 o’clock position) clearly seen on axial T2 image #11. Anterior annular fissuring is also identified. There is no herniation of nuclear material. 

Large 1 cm round synovial cyst projecting from the medial joint margin of the left zygapophyseal joint. This creates marked neural mass effect upon the cauda equina, specifically anterior displacement and compression of the traversing L4 nerve roots is noted.  The synovial cyst creates approximately 40% central stenosis. Synovial cyst seems to arise from osteoarthritic changes of the facet joints.

Diagnosis:

SYNOVIAL CYST PROJECTING FROM THE MEDIAL JOINT MARGIN OF THE LEFT L3-L4 ZYGAPOPHYSEAL JOINT. THE SYNOVIAL CYST CREATES NEURAL COMPRESSION UPON THE LEFT-SIDED NERVE ROOTS WITHIN THE CAUDA EQUINA AND APPROXIMATELY 40% CENTRAL STENOSIS.


INTERVERTEBRAL OSTEOCHONDROSIS WITH MILD LOSS OF DISC HEIGHT L3-L4 DEMONSTRATING A CONCENTRIC 12 MM ANNULAR TEAR AT THE 4-5 O’CLOCK POSITION.


Discussion: · Cystic extensions from the zygapophyseal articulations with variable content, including synovial fluid with proteinaceous or mucinous fluid, hemorrhage or air.

· Present on MR as well-defined epidural soft tissue masses with juxta-articular location and are usually seen in conjuction with obvious degenerative change of the adjoining joint.

· Central MR signal intensity varies, depending on cyst contents; non-contrast enhanced studies show high, intermediate or low T2 signal and low to intermediate T1 signal.

· Hypointensity of the outer rim on T2 images is attributed to a fibrous capsule that may have further reduced signal with hemosiderin or calcium deposition.

· Inflammatory changes are suggested as a rationale for rim enhancement with contrast-enhanced MR; typically no central enhancement.

· Differential considerations include migrated disc fragment and neurogenic cysts/tumors, but combination of location and MR signal features are usually sufficient for identification.
References:

REFERRING PHYSICIAN: AGNES KISS, DC

Comments:
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Additional Details:

Case Number: 10056848Last Updated: 09-05-2007
Anatomy: Spine and Peripheral Nervous System   Pathology: Benign Mass, Cyst
Modality: Conventional Radiograph, MRExam Date: 08-07-2007Access Level: Readable by all users
Keywords: synovial cyst, extradural mass

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