Mixed tumor of the mediastinum.

A 36-year-old asymptomatic man was found to have a large middle mediastinal mass on a chest x-ray film. At surgery the tumor was located adjacent to the carina and beneath the aortic arch. It measured 7.0 X 5.0 X 4.0 cm and was well circumscribed and soft, with mucoid areas. The histologic features were those of a benign pleomorphic adenoma of salivary gland origin. This is, to our knowledge, the first reported case of primary pleomorphic adenoma of the mediastinum. We propose an origin from the ectopic salivary gland tissue. We also describe an additional patient in whom ectopic benign salivary gland tissue was found within mediastinal lymph nodes to support our hypothesis.