Air sac adenocarcinoma of the sternum in a Quaker parrot (Myiopsitta monachus).

Respiratory neoplasia is rarely reported in avian species. A 17-yr-old Quaker parrot (Myiopsitta monachus) was admitted with a 2-wk history of anorexia, depression, and respiratory distress. Clinical examination revealed a large, firm mass in the left pectoral muscle. Radiology showed a mass silhouetting the heart and the liver. Supportive treatment was provided, but the bird died during the seventh weekly visit to drain thoracic cavity fluid. Necropsy showed a white, 3 x 3 x 2-cm, hard, gritty sternal mass. Histology showed a nonencapsulated, moderately differentiated air sac carcinoma of the sternum. Immunohistochemically the neoplasm was cytokeratin positive and vimentin and calretinin negative. This is the first report of an air sac neoplasia in a Quaker parrot and one of few respiratory tumors in psittacines.