+ 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