Roentgenologic appearance of superior mediastinal potential space lesions

Computed tomographic (CT) scans of 36 patients with tumors in the head and neck or in the anterior mediastinum were reviewed to (1) analyze invasion patterns to the superior mediastinum and (2) evaluate their contribution to the qualitative diagnosis of tumors. Invasion patterns in the superior mediastinal potential spaces can be classified into the pre-cardiovascular and central zones. Using this classification, goiter and thyroid carcinoma confined to the capsule had invaded either zone, depending on the original site of tumors. Infiltrating thyroid carcinoma tended to invade the central zone, covering the trachea, esophagus, and paratracheal nodes. This entity with a varied roentgenologic appearance may, however, be misdiagnosed as lung tumors and tracheal cancer. In the former instance, careful CT examination would help prevent confusion with the other two diseases. Thyroid carcinoma, postoperative recurrent laryngeal cancer, and thyroid malignant lymphoma were of the central zone pattern, with concomitant paratracheal node enlargement. This tendency was seen in the case of thymoma and mediastinal malignant lymphoma. Paratracheal node enlargement, as seen in Hodgkin's disease (nodular sclerosis), may occasionally allow differential diagnosis from thymoma. Invasive thymoma with central zone pattern presented roentgenologic appearance similar to that of lymphblastic non-Hodgkin's lymphoma, occasionally making it difficult to differentiate between the two entities. (Namekawa, K.)