[Thymoma in a young adult cat]

Thymomas and mediastinal lymphomas are the most common mediastinal neoplasms in cats. While mediastinal lymphoma occurs primarily in younger cats (approximately 2 to 4 years of age), thymomas are diagnosed almost exclusively in older cats. However, the following case shows that this is not necessarily always the case.A 3-year- and 11-month-old neutered male European Shorthair was presented with a preliminary report of exercise intolerance and restricted respiration. Both symptoms occurred primarily at high ambient temperatures. Radiographically, a mediastinal mass filled a significant part of the thoracic cavity. A computed tomographic examination and ultrasound-guided TruCut biopsy were performed. Histologic examination suggested a thymoma. A sternal thoracotomy and resection of the circumferential proliferation was conducted. Subsequent histopathologic examination confirmed the suspected diagnosis of a mediastinal thymoma. The cat recovered well postoperatively, and a clinical and radiographic follow-up examination was unremarkable after 8 months.