INTRODUCTIONThymoma, a rare mediastinal tumor, often requires differential diagnosis from other mediastinal masses, necessitating a multidimensional approach combining various imaging modalities and histopathologic analysis.1 Accurate correlation of these features is pivotal for drawing definitive diagnostic, prognostic, and disease staging conclusions. Moreover, the presence of local invasion complicates complete mass resection, underlining the necessity for a multidisciplinary approach in such scenarios.2,3In this case report, we detail the evaluation of a 69-year-old female presenting with recurrent left chest wall pain, subacute decline in functional status, and exertional dyspnea. Imaging disclosed a sizable anterior mediastinal mass encroaching into the pericardium and right pleural space, accompanied by loculated pericardial effusion, which was later confirmed as thymoma upon histopathological examination. This case underscores the potential complexities encountered in the diagnostic journey of thymoma, while also emphasizing the importance of an integrated approach and the challenges imposed by local invasion.