Primary mediastinal chondrosarcomas: do they really exist?

Chondrosarcomas primarily originating in the mediastinal compartment are vanishingly rare. Contrary to other unusual tumors of the mediastinum, chondrosarcomas have been described in either anterior or posterior mediastinum. The histopathological spectrum that has been described in these mediastinal tumors is similar to that described in soft tissues. In our current practice, diagnostic imaging plays an important role before any of these neoplasms is rendered as of mediastinal origin. It is also important to highlight that even though a tumor may be presenting as a mediastinal tumor, such information in essence does not constitute that the tumor is not in fact associated with another structure within the thoracic cavity, thus the importance of strict radiological correlation. Furthermore, molecular characterization of tumors that in the past were coded under the spectrum of chondrosarcomas, are now believed to represent different tumoral conditions, which raises important issues in tumor classification. Therefore, in this review, we will outline a more specific criteria regarding the diagnosis of chondrosarcomas, as wells as the essentials in the histopathological assessment of these tumors. In addition, we will discuss the current knowledge of these entities as well as their differential diagnosis, which inevitably will depend on the anatomic distribution of the tumor-anterior or posterior compartment.