Germ Cell Tumors of the Mediastinum / Thymus
Differential Diagnosis
- Most germ cell tumors are recognizable easily by their patterns
- Essentially the same as in the gonads
- Immunohistochemistry (see Supplemental Studies) may help in difficult cases
- Lymphoma can be identified with CD45a and B or T cell markers and lacks SALL4 and OCT3/4
- CD30 stains both embryonal carcinoma and some lymphomas
- Anaplastic large cell lymphoma and some mediastinal large B cell lymphomas
- Lymphoepithelioma-like carcinoma can be distinguished from seminoma and embryonal carcinoma as it is EMA positive and negative for SALL4 and OCT3/4
- Adenomatoid/reticular pattern Type A thymoma can be distinguished from yolk sac tumor by its lack of mitotic activity, Schiller-Duval bodies and hyaline globules
- SALL4 and glypican 3 not tested
