American Board of Internal Medicine (ABIM) Certification Practice Exam

In adults, a mass in the posterior mediastinum is most likely a?

1. Neurogenic tumor

2. Lymphoma

3. Thymoma

4. Teratoma

The correct answer is: Neurogenic tumor

In adults, a mass in the posterior mediastinum is most commonly associated with neurogenic tumors. The posterior mediastinum is particularly susceptible to tumors arising from the neurogenic tissues, such as nerve sheaths or sympathetic nervous system structures. Common types of neurogenic tumors include neurofibromas and schwannomas. These tumors are more frequently encountered in this location compared to other types of tumors, which may affect different mediastinal compartments or have different typical presentations. While lymphoma, thymoma, and teratoma can occur in the mediastinum, they are more commonly found in the anterior or middle mediastinum rather than being predominantly located in the posterior mediastinum. For instance, lymphoma frequently presents in lymph node-rich areas of the mediastinum and often appears in the anterior mediastinum. Thymomas, which arise from the thymus gland, are typically located in the anterior mediastinum, while teratomas, especially when malignant, generally occur in the anterior mediastinum as well. This contextual understanding of tumor locations helps emphasize that neurogenic tumors are the most likely kind to present as a mass in the posterior mediastinum for adults.