Veterinary Society of
Surgical Oncology

General Considerations

  • thymic LSA is the most common thymic tumor in cats
  • thymic LSA is less circumscribed than thymoma with local extension through the thoracic inlet, around the heart base or into the lungs, pericardium, or intercostal or cervical musculature

Clinical Features

  • mean age 4.1 years
  • breed predisposition: Siamese
  • FeLV reported in 50%-80% of thymic LSA
  • histopathologic features: neoplastic lymphocytes ranging from well-differentiated small lymphocytes to lymphoblastic and histiocytic forms
  • lymphoblastic LSA is the most common for accounting for 58% (11/19) cases
  • mediastinal LSA invading cranial vena cava (with thrombosis and cranial vena cava syndrome) has been reported


  • thoracocentesis or FNA: lymphoblasts rather than mature lymphocytes seen with thymoma
  • ultrasonography: homogenous and hypoechoic compared to mixed echogenicity with thymoma


  • chemotherapy
  • ± radiation therapy


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