2010 Radiology Exam - CT/MRI Case 2

Signalment: 4 year old, female neutered DSH Cat

History:

• coughing for 3 months
• has had several courses of antibiotics
• coughing was less frequent while cat was receiving antibiotics, but worsened as soon as medication was stopped
• thoracic radiographs showed ill-defined, focal opacity in right caudal lung lobe

See images below. Click to enlarge.

Observations:

• post-contrast images
• consolidation of the right middle lobe
• diffuse thickening of bronchial walls
• dilatation of right caudal lobar bronchus by an elongated (appearing in several adjacent images) intraluminal mass
• hyperlucency of the right caudal and accessory lobes

Synthesis:

• probable localised bronchopneumonia affecting right middle lobe
• right caudal lobar bronchial lesion could represent foreign body, granuloma or neoplasm
• hyperlucency of the right caudal and accessory lobes may represent air-trapping as a result of common bronchial obstruction
• these lesions are likely to represent the cause of cough

Management:

• bronchoscopy is indicated as a means of confirming, and possibly removing, the bronchial lesion
• Examples of errors by candidates:
• failure to recognise that the right caudal lobar lesion was elongated and bronchial lead candidates to consider differential diagnoses for a cavitary pulmonary mass
• failure to report hyperlucency of the right caudal and accessory lobes probably contributed to candidates failing to consider the possibility of bronchial obstruction
• assumption that the lesion represented a thrombus of the right caudal lobar artery (e.g. secondary to dirofilariasis) despite presence of a normal contrast-enhanced artery parallel to the bronchus.