2010 Radiology Exam - Thorax Case 1

4 year spayed female Labrador mix


  • Became acutely dyspneic on Sunday
  • Bloodwork on Monday showed mild neutrophilia and increased globulin (5.2)
  • Treated with steroids, furosemide and Baytril with no response
  • Films are from Wednesday

See images below. Click to enlarge.


  • Diffuse severe interstitial to alveolar lung pattern with symmetrical distribution
  • Multiple pleural fissure lines are visible.
  • Small amount of gas ventral to the trachea just cranial to the heart.


  • Differentials for the pulmonary pattern:
  • Non-cardiogenic pulmonary edema
  • Acute respiratory distress syndrome
  • Diffuse neoplasia (lymphosarcoma)
  • Diffuse hemorrhage
  • Pleural fissure lines
  • Subpleural localization of pulmonary infiltrates - More likely based on the fact that there is no evidence of retraction/rounding of the lung margins.
  • Minimal volume of pleural fluid
  • Minimal pneumomediastinum
  • Traumatic venapuncture ??
  • Cause unknown of limited significance


  • Serial thoracic radiography
  • Lung sampling - Fine needle aspiration or biopsy based on the interstitial localization of the pulmonary changes.


  • The majority of the candidates correctly identified the pulmonary pattern and presence of pleural fissure lines. These candidates earned full points for observations. Several of the candidates described a significant bronchial component to the pulmonary pattern. This led to an incorrect list of differential diagnoses.
  • Those candidates that performed poorly on this case did so due to inability to generate an appropriate and appropriately ranked list of differential diagnoses. Many candidates gave a primary diagnosis of lymphosarcoma even while mentioning a lack of intra-thoracic lymph node enlargement as would commonly occur with lymphosaroma. Many candidates gave a primary diagnosis of infectious disease either fungal, viral or bacterial. These candidates seemed to be overly influenced by the history of the patient.
  • Some candidates mentioned non-cardiogenic pulmonary edema as a potential diagnosis but did not rank this highly due to the diffuse and symmetric distribution of the pulmonary changes.
  • Less than 50% of the candidates included acute respiratory distress syndrome as a differential.