This from a CT scan, clinical history of sarchodsis opinion: 5.7-cm posterior mediastinal soft tissue mass abutting the left side of the t7 through t9 vertebral bodies and elevating the descending thoracic aorta anteriorly. Differential considerations in

Sarcoidosis . Sarcoidosis is a diagnosis of exclusion that requires biopsy/histologic evaluation and exclusion of other diseases including lymphoma. A 5.7 cm posterior mediastinal mass warrants evaluation by a thoracic surgeon.
Sarcoid mass. Sounds like a sarcoid mass. Make you sure you follow up with your doctor as there are other possibilities, like lymphoma.