Most thymomas are slow-growing tumors. This is determined at surgery and is not a histologic diagnosis. Local invasion of the pleura occurs frequently. Distant metastases are infrequent. The signal characteristics are not adequate, however, to differentiate benign from malignant thymomas.
Calcification is demonstrated in a minority of patients with thymoma.
All rights reserved. From Hungaria this is a very big thymoma Malignant thymoma, external appearance, shows a large tumor with variegated appearance typical of this lesion. Ovoid, nodular, well-circumscribed, tan mass. A medium-high power view of a single lobe of a normal thymus. At this power, the organization of the thymus into a deeper staining cortex and a more likely staining medulla is more clear.