Imaging and Staging of Thymic Tumors

The thymus is a primary lymphoid organ located in the upper prevascular mediastinum. A number of masses arise in relation to the thymus. Accurate knowledge of anatomy and imaging features is essential for the differentiation between non-tumoral thymic pathology and malignant thymic tumors. In general, a benign hyperplasia of the thymus occurs in children and young adults, while in adults thymoma is the most common tumor. Furthermore imaging is of great importance in the preoperative staging and (oncological) follow-up. Computed tomography (CT) is the imaging modality of choice to assess the mediastinal structures, including the thymus. Medical imaging is essential to further characterize those lesions that warrant further workup. Surgery is the gold standard for the treatment of thymoma with the aim of complete resection. We provide an overview of thymic masses with typically imaging features: thymic hyperplasia, thymic cyst, thymolipoma, thymoma, thymic carcinoma, and thymic carcinoid. Lymphoma will be discussed in Chapter 15: Imaging of Non-thymic Mediastinal Tumors.