History: European Shorthair cat, 18 years, female
Diagnosis: Lung: pulmonary adenocarcinoma with partial compression atelectasis of the accessory lung lobe and multifocal metastases
Description: A large pale firm mass of about 4.7 x 3.1 x 1.9 cm with a central retraction (“umbilicated appearance”) replaces and expands the accessory lobe. The remaining lung lobe is partially atelectatic, most likely due to compression. Additional smaller masses are present in the left cranial and diaphragmatic lung lobes. The right middle and especially the diaphragmatic lobes are expanded by mild alveolar emphysema.
Comments: The cat had been treated for a long time because of renal and cardiac insufficiency and additionally developed dyspnoea before she was found dead. Pulmonary adenocarcinomas are a common finding in older cats. Tumours arising close to the bifurcation or major large bronchi are usually of bronchoepithelial origin. As in this case, they tend to be large and solitary with infrequent metastasis to the periphery of the lung. Peripheral metastatic spread to the digital bones is a common finding in progressed stages.