Mixed thymic tumor in a rooster: gross and histological features

A 2-year-old rooster local breed suffered from anorexia, emaciation with an abnormal large mass in the lateral side in the cervical region was attended to Veterinary Teaching Hospital belong to College of Veterinary Medicine, Mosul University. After physical examination a movable and friable mass was recognized in the cervical region, the case sends for surgical intervention. Gross examination of the removed mass showed a friable, pale, will capsulated with hemorrhagic areas. Microscopically, the mass included three types of tumors. Squamous cell thymic carcinoma characterized by the presence of keratin pearl. Lymphoma that characterized by atypical polymorphic lymphocytes, vesicular nucleus, and pyknotic nucleoli, while cytoplasm appears eosinophilic to granular with illdefine borders. Lipoma which appears as irregular shape of adipocytes that lack their nucleus, with scattered infiltration of pyknotic lymphocytes. This is the first pathological report of mixed tumor of the thymus gland in rooster that composed from squamous cell thymic carcinoma, lymphoma and lipoma.