Thymomas affect men and women with equal frequency, generally afflicting adults above 40 years of age. Sudden cardiac death due to right artrial compression may occur. Thymomas may be associated with myasthenia gravis, and other systemic disorders including pure red-cell aplasia, hypogammaglobinaemia, endocrine, and connective tissue disorders. Imaging Findings Radiographs of chest reveal a contour abnormality of the anterior mediastinum, as the mass displaces both visceral and parietal pleura, resulting in smoothly marginated lobulated borders against the lung. They may extend to both sides of the mediastinum or may arise in the cardiophrenic angle.
Calcification is common, is usually linear, thin and peripheral.
Intravenous iodinated contrast allows enhancement of vascularity, enabling the accurate assessment of tissue planes and the separation of mediastinal structures. On CT, replacement of the anterior mediastinal fat by denser soft tissue is the primary sign. The mass is usually in close approximation to the root of the aorta and the pulmonary artery, and may be partially or completely outlined by fat. Mediastinal involvement by thymomas is usually intrathoracic and mostly pleural. Although CT is a good predictor of the invasive character of a thymoma, adhesions can mimic invasions, and invasion could be missed if the cleavage plane between the tumor and the involved structure is close to the plane of scanning.