Medical imaging of thymoma in a dog

Abstract

A 15-year-old, castrated male shih-tzu dog was referred to Veterinary Medical Teaching Hospital of Gyeongsang National University due to dyspnea, anorexia, depression of 1 week's duration. On thoracic radiography, triangular shaped soft tissue opacity mass presented in the left cranial lung lobe region. On computed tomography, there was a 3.8 × 2.5 cm mass in the left thoracic cavity, which was lobulated and adhered to ventral pleural surface. Histopathologically, the neoplastic cell population consisted of a lot of lymphocytes and a few of Hassal's corpuscles. The immunohistochemistry, lymphocytes were diffusely positive for CD3 and focal positive CD79α. Based on gross, histologic, and immunohistochemical findings, the neoplasm was diagnosed a lymphocyte predominant thymoma.