A 29 year old woman had a screening chest x-ray (PA and lateral shown) prior to routine cholecystectomy. The physical examination was otherwise unremarkable. An MRI (also shown) of the chest was obtained. The lesion pictured is 

A. best treated by radiation and chemotherapy. 
B. considered unresectable. 
C. further evaluated by myelography.
D. a ganglioneuroma in greater than 50% of cases. 
E. resected without histologic confirmation. 

Answer E

Mediastinal neurogenic tumors in adults are most frequently asymptomatic and found on routine radiographs. Essentially all isolated neurogenic tumors are amenable to surgical therapy and the best outcome follows complete resection. In slightly less than 10% of cases, the tumor protrudes into or through the neural foramina into the spinal canal ("dumbbell tumor"). Nerve sheath tumors account for 90% of these cases. Computed tomography confirms the presence of intracanal tumor, and magnetic resonance imaging allows the precise identification of its extent. Myelography is seldom used.

Treatment of the dumbbell tumor requires an integrated surgical approach by the thoracic and neurosurgeons to obtain complete resection of all tumor. Incomplete or inadequate removal of the tumor may result from a thoracic approach alone. Aggressive resection of soft tissue extending into the neural foramina carries the risk of uncontrolled bleeding into the spinal canal. Laminectomy and resection of the intraspinous component of the tumor is an appropriate first step.

The prognosis is excellent for benign tumors. For malignant tumors (malignant schwannoma), radiation therapy may be indicated following resection.