Saber-Sheath Trachea

Saber-sheath trachea is the term for the narrow bowed tracheal air column seen on chest radiographs (Figure 1) of patients with chronic obstructive pulmonary disease (COPD). It was Reginald Greene and Gerhard Lechner ² who first associated this tracheal abnormality with patients who had altered pulmonary function. The term, alterssabelscheidentrachea (saber-sheath trachea), had previously been used by pathologists who seem to have regarded it as a normal consequence of aging ² . Greene and Lechner presented data from 13 patients seen at the Massachusetts General Hospital. The coronal diameter of the intrathoracic trachea in each patient was one-half or less that of the corresponding sagittal diameter. On frontal and lateral chest radiographs, this finding allows the radiologist to suggest the diagnosis of COPD. Clinical information and pulmonary function data supported the diagnosis of COPD in Greene and Lechners cases. Recognition of the saber-sheath abnormality as a sign of COPD has been emphasized since tracheal compression or distortion in other planes may be indicative of a mediastinal mass. Figure 1 Saber-sheath trachea seen in ‘anteroposterior (left) and lateral tomographic sections (right) through the intrathoracic trachea. Note the abrupt change from marked coronal narrowing to a more rounded shape at the thoracic outlet.’ Reprinted from Greene and Lechner<xref ref-type="bibr" rid="ref71_1"> ¹ </xref>. ‘Saber-Sheath’ trachea: a clinical and functional study of marked coronal narrowing of the intrathoracic trachea. <italic>Radiology, 1</italic>975, 115, 265–268, with permission of the RSNA https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003076568/34c29fd5-5662-4e8f-b58c-badd7fa5d724/content/fig71_1_B.jpg"/>