|
| Images
below require Macromedia's Flash Player to view |
 |
Neuroradiology Case of the Week
Case 348
September 2008
Nate Johnson, MD
Clinical
Presentation: Patient is a 20-year-old male with acute onset of back pain after playing football. No resolution of pain for several weeks so patient sought medical attention.
Imaging Findings: See below
|
Figure 1 - Sagittal axial T2 MR image: Predominately high T2 signal lesion involving right pedicle, adjacent pars and superior facet region of L3.
|
|
Figure 2 - Axial PD Image: Intermediate-high signal intensity of above described lesion.
|
|
Figure 3 - Coronal T1 MR Image: Coronal sequences demonstrate central low T1 signal with more peripheral high T2 signal rim-like enhancement.
|
|
| Figure 4 - Biopsy: Fluoroscopic-guided biopsy of the lesion yielded blood, no neoplastic cells. |
Diagnosis: Aneurysmal unicameral bone cyst - spine (pathology proven)
Discussion: Aneurysmal bone cysts are blood-filled cystic cavities that are osteolytic and expansile with a thin wall arising in medullary canal of metaphysis. CT is the examination of choice to evaluate these findings. The name of the lesion is derived from its "aneurysmal" appearance radiographically. These patients commonly present with acute onset of pain which worsens over the next few weeks as did our patient.
This is a disease of the young with the bulk occurring before the age of 30 and 75% before age 20. Almost 50% of these lesions are located in the upper extremity or the lower leg, split nearly equally among the two. The next places to look are the spine, femur and pelvis since these 3 split the next 40% of the lesions. The last 10% can be found scattered from the skull, ribs, clavicles or feet.
Spinal lesions make up 16% of aneurysmal bone cysts. The lesion is most likely to occur in the posterior elements and can extend into multiple vertebral bodies, soft tissues and the spinal canal. Secondary to spinal canal invasion neurologic symptoms can be a presenting symptom.
MRI findings of an aneurysmal bone cyst include low to intermediate signal intensity on T1-weighted images, although acute hemorrhage will demonstrate a high signal intensity component. T2-weighted images can be variable based on the composition of the cyst. Low to intermediate signal intensity is common with areas of heterogeneous high signal intensity. Septations may be present. Another feature to look out for in aneurysmal bone cysts is a fluid-fluid level. This is a non-specific finding since many other entities can demonstrate this finding but it is supportive.
References:
-
Kransdorf MJ, Sweet DE. Aneurysmal bone cyst: concept, controversy, clinical presentation, and imaging. AJR Am J Roentgenol. 1995 Mar;164(3):573-80. [PubMed]
- Capanna R, Albisinni U, Picci P, Calderoni P, Campanacci M, Springfield DS. Aneurysmal bone cyst of the spine. J Bone Joint Surg Am. 1985 Apr;67(4):527-31. [PubMed]
- Cottalorda J, Bourelle S. Modern concepts of primary aneurysmal bone cyst. Arch Orthop Trauma Surg. 2007 Feb;127(2):105-14. [PubMed]
- Sullivan RJ, Meyer JS, Dormans JP, Davidson RS. Diagnosing aneurysmal and unicameral bone cysts with magnetic resonance imaging. Clin Orthop Relat Res. 1999 Sep;(366):186-90. [PubMed]
- Capanna R, Campanacci DA, Manfrini M. Unicameral and aneurysmal bone cysts. Orthop Clin North Am. 1996 Jul;27(3):605-14. [PubMed]
|
