A case of primary pulmonary adenocarcinoma in a German Shepherd dog

Primary lung tumours are rare in dogs, but metastasis of other tumours to lungs is common. The present report describes a case of primary pulmonary adenocarcinoma with metastasis in the mediastinal lymph node and liver in an eight-year-old German Shepherd female. Grossly, lungs revealed severe multifocal distinct, white-tan, firm neoplastic foci ranging from 3–5 cm in diameter involving all lobes. Microscopically, sections of lungs revealed multifocal, variably sized, unencapsulated, well-demarcated, expansile neoplastic foci arranged in glandular pattern with moderate amount of connective tissue. The glands were oval to round in shape containing small quantity of mucin. Acini were composed of a single layer of cuboidal epithelial cells compressing adjacent pulmonary parenchyma. Neoplastic cells revealed variably distinct cell borders, mild nuclear atypia with round to oval nuclei, and moderate amount of eosinophilic cytoplasm. Mitotic figures were 3–4 per 10 high power fields. Mediastinal lymph nodes revealed metastatic neoplastic foci in lymphatics and along the medullary cords. Liver revealed subcapsular metastatic foci.