Veterinary Society of
Surgical Oncology

General Considerations

  • thymic LSA is the most common thymic tumor in dogs
  • 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 Presentation

  • mean age 5.8 years
  • breed predisposition: none
  • neurologic signs due to direct infiltration into thoracolumbar spinal cord
  • polyostotic bone involvement reported in puppy with thymic LSA
  • canine thymic LSA is frequently associated with hypercalcemia (25%-50%) and generalized lymphadenopathy
  • histopathologic features: neoplastic lymphocytes ranging from well-differentiated small lymphocytes to lymphoblastic and histiocytic forms
  • lymphoblastic LSA is the most common form accounting for 75% (8/12) cases

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

CRANIAL MEDIASTINAL LYMPHOSARCOMA

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