Cavitary pulmonary lesion wall thickness, presence of additional nodules, and intralesional contrast enhancement are associated with malignancy in dogs and cats.

Objective: To investigate the CT features of cavitary pulmonary lesions and determine their utility to differentiate malignant from benign lesions.

Animals: This retrospective study included cases from 5 veterinary medical centers between January 1 2010, and December 31, 2020. Inclusion criteria included having a gas-filled cavitary pulmonary lesion on thoracic CT and definitive diagnosis by either cytology or histopathology. Forty-two animals (27 dogs and 15 cats) were included in this study.

Procedures: Medical records systems/imaging databases were searched, and cases meeting inclusion criteria were selected. The CT studies were interpreted by a third-year radiology resident, and findings were reviewed by a board-certified veterinary radiologist.

Results: 7 of the 13 lesion characteristics investigated were not statistically associated with the final diagnosis of the lesion, whereas 6 were statistically associated. Those that were associated included the presence of intralesional contrast enhancement, type of intralesional contrast enhancement (heterogenous and homogenous analyzed separately), presence of additional nodules, wall thickness of the lesion at its thickest point, and wall thickness at the thinnest point.

Clinical Relevance: Results from the present study showed that thoracic CT imaging of cavitary pulmonary lesions can be used to further refine the list of differential diagnoses. Based on this data set, in lesions that have heterogenous contrast enhancement, additional pulmonary nodules, and wall thickness > 40 mm at their thickest point, it would be reasonable to consider malignant neoplastic disease higher on the list of differentials than other causes.