2010 Radiology Exam - Spec Proced/NM Case 2

Signalment: 1.5 year old MC mixed breed dog

History: Front limb stiffness and rear limb paresis for 2 weeks

3 lateral views and 4 VD views of a myelogram of the cervical and cranial thoracic spine were provided to the candidate. CT images and/or thoracic radiographs were available upon request.

See images below. Click to enlarge.

Observations

• Attenuation and dorsal deviation of ventral contrast column over the body of T5 and the intervertebral disc space T5/6, dorsal contrast column only mildly attenuated
• Widening of the intervertebral foramen T5/6
• VD views difficult to assess due to location of lesion, but leftward deviation of right contrast column in area of interest and area of increased opacity noted superimposed over right lung fields (lateral to cardiac silhouette)

Synthesis

• Extradural compressive lesion cranial thoracic spine due to a large right sided dorsal thoracic mass
• Widening of intervertebral foramen suggestive of extension of mass from thorax into vertebral canal or vice versa
• Differential diagnoses: Neoplasia (e.g. soft tissue sarcoma, nerve sheath tumor, neuroendocrine tumor); inflammatory mass lesion (granuloma, abscess)

Case Management
Further imaging:

• Oblique views to be able to better evaluate area of interest
• Cross-sectional imaging (CT/MRI) for further evaluation
• Thoracic radiographs
• (CT and/or thoracic radiographs available upon request)
• CT/US guided biopsy

Challenges

• Inappropriate description/interpretation of myelogram findings: (1) Failure to classify lesion as extradural, and (2) Assumption that degree of cord compression is insignificant and that actual lesion is not present on films provided
• Failure to appreciate thoracic mass ventral to spine on radiographs
• Failure to appreciate thoracic mass on CT (if CT requested)
• Failure to list appropriate differential diagnoses
• Misinterpretation of normal structures as lesions