Pulmonary carcinoma associated with cystic airspaces in two dogs.

Malignant pulmonary neoplasia associated with cystic airspaces is a well-recognised disease entity in humans. Two elderly dogs, previously diagnosed with a solitary emphysematous bulla, presented with non-specific clinical signs. At presentation, pulmonary auscultation was unremarkable. In both cases, thoracic CT demonstrated the transformation of the cystic airspace lesions characterised by a progressive increase of the solid component and reduction of the air component. Cytological evaluation and subsequent surgical excision followed by histopathology confirmed pulmonary carcinoma in both cases. These two cases represent the first demonstration of possible malignant transformation of pulmonary cystic airspace in dogs. Veterinarians should consider neoplastic transformation as a differential diagnosis in cases of cystic airspaces, particularly cases with features including thickening or irregularity of the wall, associated soft-tissue nodules or solid and non-solid tissue intermixed within clusters of multiple cystic airspaces. Ongoing monitoring of cystic airspace lesions through diagnostic imaging is recommended.