¹⁸ F-FDG PET/CT revealed an invasive thymoma extending into the superior vena cava and right atrium

Although generally benign, thymomas have the potential to be malignant due to their tendency for local invasion and occasional development of distant metastases. They are characterized by infiltration and extension into adjacent structures, with metastasis typically confined to the pleura, pericardium, or diaphragm. In this case, a rare instance of invasive AB-type thymoma located in the anterior mediastinum is reported, which had invaded the superior vena cava and extended caudally into the right atrium. ¹⁸ F-fluorodeoxyglucose ( ¹⁸ F-FDG) PET/CT clearly defined the size and characteristics of the lesion, providing valuable information for patient management.