Thymic lymphosarcoma with brain involvement in a Holstein heifer.

An 8-month-old Holstein heifer with cervical enlargement was suspected of thymic lymphosarcoma given clinical signs of depression, tendency to lie down, cervical mass, jugular vein distension, conjunctival hyperemia, and ruminal tympany. Unilateral Horner's syndrome was also observed. Increased serum total lactate dehydrogenase (LDH), LDH isozyme (LDH-2, and LDH-3) and serum thymidine kinase activity were observed. The findings of fine needle aspiration cytology of the cervical mass revealed large lymphoblasts with mitoses present. These findings strongly suggested the diagnosis of lymphosarcoma. Necropsy revealed a large mass in the cervical thymic region, which compressed the esophagus and trachea. Cranial masses in the frontal sinus and multiple extradural sites throughout the cranial vault were also recorded. Histopathological examination confirmed the diagnosis of thymic lymphosarcoma and demonstrated the brain involvement of neoplastic lymphoid cells in the cerebrum. This is a rare clinical case of thymic lymphosarcoma accompanied by brain metastasis in a Holstein heifer.