Some anatomical variants and pitfalls in computed tomography of the trachea and mainstem bronchi. II. Compression or anatomical variants?

472 computed tomographic (CT) examinations in 448 patients were reviewed for depression of the wall of the trachea and mainstem bronchi. Depression was defined as a neutral term, not indicating pressure exerted upon the wall. Such depressions appeared to occur very frequently as a variant. Special attention is paid to the so-called azygos vein indentation. The most marked depression variants in our series are reproduced. When a depression is found in contiguity with a pathological mass and does not exceed the range of the variants, one cannot be sure that the mass is indeed the cause of this depression. In patients with bronchogenic carcinoma, depression of the wall of the trachea or mainstem bronchus seems to be no better sign for the metastatic nature of lymphadenopathy than size per se.