True statements regarding patients with a mediastinal mass include:

A. Asymptomatic patients have a benign mass in over 75% of cases.

B. Symptomatic patients are more likely to have a malignant lesion than a benign lesion

DISCUSSION: Seventy-six per cent of the asymptomatic patients with a mediastinal mass seen in one series over a recent 20-year period had a benign leison. In contrast, 62% of the symptomatic patients had a malignant neoplasm during this period. A number of intrathoracic and extrathoracic lesions may have an appearance similar to a primary mediastinal mass on routine chest films, as do a large number of cardiovascular lesions. Although angiography was used in the past for this differentiation, CT with contrast and MRI now distinguish a primary mediastinal mass from a cardiovascular lesion. Tru-cut needle biopsy of a cardiovascular lesion may be associated with significant hemorrhagic complications. Seminomas rarely produce beta–human chorionic gonadotropin and never produce alpha-fetoprotein. In contrast, over 90% of the nonseminomas secrete one or both of these hormones.