2009 Radiology Exam - Abdomen Case 2

Signalment: Adult male castrated canine Springer Spaniel

Hx: Seizures. Suspect mass palpated. (Films were identified as copy films)

See images below. Click to enlarge.

Radiographic Findings:

• Large ovoid FAT opaque mass with wispy internal soft tissue opacities and a rim of soft tissue opacity in the mid caudoventral abdomen.
• Abdominal structures (intestines) displaced by mass.
• Gastric axis mildly caudodorsally displaced
• Smooth ventral bone proliferation along the vertebral endplates at L7-S1.
• Small irregular shaped metal/mineral opacities in the gastrointestinal tract - incidental finding.

DDX:

• Intra-abdominal fat mass, primary differential is lipoma or less likely liposarcoma.
• Mild hepatomegaly - various causes.
• Gastrointestinal foreign bodies - incidental.
• Lumbosacral spondylosis deformans - incidental.

Recommendations:

• Ultrasound to obtain fine needle aspirates or biopsy. If surgery is considered, computed tomography could be used to evaluate the extent.
• An alternative approach for the lipoma would be to do nothing at the moment. If there are no clinical signs from a mass effect, it is likely incidental.
• Further workup for the seizures is warranted (ie. magnetic resonance imaging of the brain) as the mass is unlikely to be related to the seizures.

Follow up: The dog had the mass surgically removed and a lipoma with coagulative ischemic necrosis was diagnosed on histopathology.

Candidate Performance: This case was selected to test the candidates on recognition of radiographic opacities. Candidates that determined the mass was FAT opaque did very well on the case, as the list of differential diagnoses is limited. Although a few candidates did not initially see it was fat opaque, several were able to reason it out. As one candidate stated, the mass is as big as the bladder but not as opaque- therefore it is not soft tissue opaque. Many candidates misidentified the mass as soft tissue opaque with a possible mineralized rim and therefore the list of differentials would be incorrect (with paraprostatic cyst being the most commonly listed). Candidates were neither penalized nor rewarded for discussion of the liver as it is equivocal.