2007 Radiology Exam - Alternate Imaging Case 2

Information provided to candidate

• Thoroughbred
• 1 year
• Female
• Draining wound right hind metatarsophalangeal joint region for 1 month. Has a grade V/V lameness
• Available images are lateral, DPl, DMPlO views of the right hind fetlock region, obtained after hours

State the findings

• Generate a prioritized differential diagnosis list.
• Are other imaging studies indicated? Justify.
• Do the imaging findings explain the clinical signs? Justify.

See images below. Click to enlarge.

Findings expected from candidate

• Candidates were expected to describe intracapsular and extracapsular soft tissue swelling, gas opacities in the soft tissues, and absence of bone lysis or proliferation. Noting overexposure artifacts was accepted, but not required.

Differentials expected from candidate

• Cellulitis, tendonitis/tenosynovitis, arthritis.

Other imaging studies expected

• Sinogram to assess extent of involvement of draining wound

Findings from additional studies

• Candidates were expected to describe contrast opacification of the draining wound and digital flexor tendon sheath. Description of irregular filling defects in the tendon sheath was also expected. Candidates were expected to state that opacification of the metatarsophalangeal joint was not seen.

Correlation between imaging findings and clinical signs

• Candidates were expected to indicate that both the clinical and imaging findings were consistent with tendonitis/tenosynovitis secondary to penetrating soft tissue trauma. A poor prognosis was warranted.

Summary of overall candidate performance

• Most candidates performed adequately on this case. A few noted that the soft tissue swelling was both intracapsular and extracapsular. Nearly all asked for the sinogram. Some neglected to mention whether the joint was involved without prompting. A few diagnosed the tendon as a wooden foreign body in the sinogram.

Followup

• The horse was euthanized and a necropsy was performed. The skin wound communicated with the tendon sheath and there was also a laceration in the superficial digital flexor tendon. Exudate and proliferative synovial tissue were present within the tendon sheath.