Objective: Mediastinal masses are a group of heterogenous lesions which may be a coincidental finding or present with symptoms. More than half of mediastinal lesions are located in the prevascular mediastinum. As these tumors are not often encountered in clinical routine, making a diagnosis with a high degree of confidence may seem challenging.

Methods: The latest computed tomography (CT)-based classification of the mediastinal compartments by the International Thymic Malignancy Interest Group (ITMIG) moves away from earlier radiograph-based classification systems and helps to reliably classify tumors based on location, although in some cases the lesion can occupy more than one compartment. Methods: Radiology plays an important role in the evaluation of anterior mediastinal lesions. Although in some cases imaging features alone allow a diagnosis to be made; in other cases knowledge of important radiological features and their analysis in the context of patient factors like age and duration of symptoms can help to narrow down the differential diagnosis, avoid unnecessary workup, and guide further steps.

Conclusions: Computed tomography (CT) is central for the characterization of mediastinal masses in clinical routine. In some situations, like in the case of thymic cysts or thymic hyperplasia, magnetic resonance imaging (MRI) can be used as a noninvasive problem-solving tool.