mediastinoscopy

mediastinoscopy, medical examination of the mediastinum (the region between the lungs and behind the sternum, or breastbone) using a lighted instrument known as a mediastinoscope. Because the region of the mediastinum contains the heart, trachea, esophagus, and thymus gland, as well as a set of lymph nodes, mediastinoscopy can be used to evaluate and diagnose a variety of thoracic diseases, including tuberculosis and sarcoidosis (a disease characterized by the formation of small grainy lumps within...