A 20.5 cm Malignant Peripheral Nerve Sheath Tumor of the Anterior Mediastinum Showing Response to Neoadjuvant Therapy.

Malignant peripheral nerve sheath tumors (MPNST) are a rare form of sarcoma derived from Schwann cells. Major risk factors for development are neurofibromatosis 1 (NF1) and prior radiation exposure. Tumor location is highly variable. We present a case of an extremely large MPNST tumor in the anterior mediastinum in a 66-year-old male. To the best of our knowledge, the 20.5 cm tumor is the first of its kind in a patient without clinical signs of NF1 or prior radiation exposure. The localization of this tumor to the anterior mediastinum is rarer, as the most common tumors presenting in this area are thyroid neoplasms, thymomas, teratomas, and lymphomas. The patient's tumor responded to doxorubicin-ifosfamide-mesna-based therapy. The tumor decreased from 20.5 cm to 9.0 cm on subsequent imaging. Thus, this is an interesting and valuable case to learn about the presentation and potential treatments of such a rare pathology.