SINGLE unilateral circumscribed mediastinal tumors of lymphoblastic origin are infrequently encountered. Their roentgenologic appearance closely simulates that of mediastinal tumors of the dermoid or teratomatous type. The correct preoperative diagnosis may be difficult to establish, as the lymphoblastic nature of the tumor may not be suspected. Furthermore, even when it is suspected, the response to a test dose of radiation occasionally is so limited that this method of differential diagnosis may prove to be fallacious.
The purpose of this study is to report 4 cases of lymphoblastic mediastinal tumors which have been removed at the University of Michigan Hospital during the past ten years. In 3 of the cases the correct diagnosis was not suspected before operation. In the fourth case, the diagnosis of a lymphoblastic tumor was considered; a test dose of radiation was advised but was not given as had been planned. In each instance the tumor was