case_images: PMC11740314_01
case_images: (A, B) Initially, an abdominal ultrasound (A, subcostal plane) was performed, revealing a 7.3 x 5.4 cm mass. Consequently, the on-call cardiologist performed a transthoracic echocardiogram (B and see Supplementary material online, Video S1, four-chamber plane), identifying a heterogeneous, poorly defined mass attached to the lateral wall of the right atrium, associated with a pericardial effusion, without being able to precisely delineate its extracardiac extension. (C, D) CT images were performed to evaluate the extracardiac extension of the mass. They reveal a heterogeneous, calcified mass originating from the anterior mediastinum, infiltrating the superior vena cava and the right atrium. (E, F) PET-CT images were requested to aid in the diagnostic orientation of the nature of the mass, revealing intense metabolic activity, consistent with its aggressive presentation and malignant behaviour. (G, H) Pathology of the mass. An intense lymphoplasmacytic infiltrate with areas of sclerosis is evident. However, the entire surgical specimen could not be analysed, making it impossible to rule out the coexistence of anatomopathological findings suggestive of malignancy, especially given the aggressive behaviour and intense metabolic uptake observed. M, mass; L, liver; LA, left atria; LV, left ventricle; PE, pericardial effusion; RA, right atria; RV, right ventricle; SCV, superior cava vein.
case_images: ytae699f1.jpg
case_images: PMC11740314_01_ytae699f1.jpg
case_images: ytae699-F1
case_images: Further multimodal imaging techniques (Figure 1;  Supplementary material online, Video S1) confirmed a high-grade thymic tumour, ultimately diagnosed as thymosarcoma infiltrating the superior cava vein (SCV) and right cardiac chambers.