American Board of Surgery Qualifying Exam (ABS QE) Practice Test

Which tumor is categorized as the most common germ cell tumor found in the mediastinum?

1. Seminoma

2. Teratoma

3. Thymoma

4. Neurogenic tumors

The correct answer is: Teratoma

The most common germ cell tumor found in the mediastinum is indeed a teratoma. Teratomas are unique in that they can contain multiple types of tissue, such as hair, muscle, and even organ-like structures. They can be found in various locations within the body, including the mediastinum, where they are particularly common in young adults and adolescents. Teratomas in the mediastinum are usually of the mixed type, containing components that represent all three germ layers (ectoderm, mesoderm, and endoderm). Their prevalence in this area is significant compared to other types of germ cell tumors, such as seminomas, which are more often encountered in the testis rather than in the mediastinum. While thymomas and neurogenic tumors are relevant in discussions of mediastinal pathology, they do not fall under the classification of germ cell tumors and are not as prolific as teratomas in this specific location. This distinction underscores why teratomas hold the title of the most common germ cell tumor in the mediastinum.