Today’s case is a 10-year-old female neutered domestic short hair cat with labored breathing.
There is a very large mass in the cranial mediastinum that is displacing the trachea dorsally and the heart caudodorsally. On the dorsoventral projection, the cardiac silhouette is displaced to the right and the mass occupies most of the left hemithorax. The lungs are retracted with rounded borders due to compression by the mass. In the portion of the abdomen included, the liver and spleen are mildly enlarged. The diaphragm is flattened due to hyperinflation. There is mineralization in the right renal pelvis.
Differential diagnoses for a cranial mediastinal mass include thymoma, lymphoma, or less likely branchial cyst, ectopic thyroid, granuloma, or abscess. Chronic renal change. Hepatic and splenic enlargement may be metabolic, congestion, or degenerative.