+ 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

+ Diagnosis

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

+ Treatment

  • Chemotherapy
  • ± Radiation Therapy