Teratomas of the mediastinum.

Mediastinal teratomas are rare, constituting only 8-13% of tumours in this region. Teratomas often contain structures from all three germ layers, and 15-20% are malignant. A report is presented of eight patients operated on in 1978-1985 for mediastinal teratoma histologically classified as benign. Radical excision was performed in seven cases, but one tumour could not be radically removed because of infiltrative growth into vital structures, and the patient died 9 months postoperatively. In the other seven cases, including four with unusually rapid and dramatic tumour development, no signs of recurrence have appeared.