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Year : 2021  |  Volume : 4  |  Issue : 1  |  Page : 51-52

Morphological variant of trachea in chronic obstructive pulmonary disease patients

Department of Respiratory Medicine, Sundaram Medical Foundation, Chennai, Tamil Nadu, India

Date of Submission21-Apr-2021
Date of Acceptance26-Jun-2021
Date of Web Publication22-Sep-2021

Correspondence Address:
Department of Respiratory Medicine, Sundaram Medical Foundation, Chennai, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/japt.japt_21_21

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How to cite this article:
Fauzi, Sridhar R. Morphological variant of trachea in chronic obstructive pulmonary disease patients. J Assoc Pulmonologist Tamilnadu 2021;4:51-2

How to cite this URL:
Fauzi, Sridhar R. Morphological variant of trachea in chronic obstructive pulmonary disease patients. J Assoc Pulmonologist Tamilnadu [serial online] 2021 [cited 2022 Jan 28];4:51-2. Available from: http://www.japt.com/text.asp?2021/4/1/51/326408

An 88-year-old gentleman with a chronic history of smoking, a known case of Systemic Hypertension SHTN/chronic obstructive pulmonary disease (COPD)/hypothyroidism/Parkinson's disease, presented with complaints of drowsiness and sudden-onset dyspnea with desaturation up to 85% in room air. Auscultation of the chest revealed bilateral wheeze and crepitations. COVID reverse transcription polymerase chain reaction was negative. Chest X-ray revealed bilateral lower zone haziness. Computed tomography (CT) of the chest screening revealed emphysematous changes in both lungs with small bullae and mild bronchiectasis in the right lower lobe [Figure 1] and [Figure 2]. Arterial blood gas (ABG) was suggestive of severe respiratory acidosis and hypoxemia.
Figure 1: CT scan lung window

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Figure 2: CT scan mediastinal window

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  Radiological Image Top

  1. What is the radiological description?
  2. What is the common condition associated with this tracheal abnormality?
  3. Which are the other conditions where you may get this abnormality?
  4. How do you diagnose it?
  5. What is the likely differential diagnosis that has to be ruled out?

  Answers Top

  1. Saber-sheath trachea
  2. COPD
  3. Bronchiolitis obliterans syndrome following lung transplantation and chronic bronchitis
  4. Tracheal index <0.6
  5. Mediastinal mass.

  Discussion Top

“Saber” literally, as stated in Encarta 2001, is a heavy cavalry sword with a slightly curved blade that is sharp on one edge. “Sheath” is a close-fitting covering or a case for the sword. Saber-sheath trachea is an acquired morphological abnormality of the intrathoracic trachea. It is characterized by marked decrease in coronal (lateral) diameter and an associated increase in sagittal (anteroposterior) diameter of the intrathoracic trachea.[1] However, the extrathoracic (cervical) trachea is spared. It is pathognomonic for COPD and is more commonly seen in men than in women. This deformity of the trachea is believed to result from repeated injury to the intrathoracic trachea from chronic coughing. Perhaps, the saber-sheath shape is an expression of how the injured trachea remodels itself in an abnormally shaped thorax. A study conducted by Greene published in 1978 concluded that patients with COPD do not necessarily have saber-sheath tracheas, but its presence highly suggests the diagnosis.[1] Hence, the specificity of saber-sheath trachea in COPD is 95%, whereas sensitivity is <10%. It may also be seen in bronchiolitis obliterans syndrome following lung transplantation and chronic bronchitis.[2] Saber-sheath trachea is linked to the functional severity of airway obstruction. One study showed a direct correlation between pulmonary outflow obstruction and the extent of the anomaly. However, other study suggests that saber-shaped trachea is just a morphological sign of hyperinflation more than that of obstruction.[3] Saber-sheath trachea diagnosis is made when the tracheal index on CT is lower than 0.67. This index is defined as the ratio of the coronal and sagittal tracheal diameters in the axial plane, usually taken 1 cm above the upper edge of the aortic arch.[4] Chest X-ray is normal in 45% of cases. Bronchoscopy confirms the diagnosis and establishes the degree of expiratory collapse. There is no specific treatment for this entity. It should not be mistaken for narrowing due to a mediastinal mass. It is a rigid, fixed abnormality that should not be confused with tracheomalacia. Saber-sheath trachea may give rise to unexpected ventilation difficulties if not diagnosed before intubation.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initial s will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


Thanks to the Department of Pulmonology and General Medicine, Sundaram Medical Foundation, Chennai.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Greene R, Lechner GL. “Saber-Sheath” Trachea: A clinical and functional study of marked coronal narrowing of the intrathoracic trachea. Radiology 1975;115:265-8.  Back to cited text no. 1
Guinde J, Georges S, Bourinet V, Laroumagne S, Astoul P, Dutau H. “Kissing nodules” in saber-sheath trachea. Respiration 2018;95:464.  Back to cited text no. 2
Rubenstein J, Weisbrod G, Steinhardt MI. Atypical appearances of “saber-sheath” trachea. Radiology 1978;127:41-2.  Back to cited text no. 3
Ismail SA, Mehta AC. “Saber-sheath” trachea. J Bronchol Int Pulmonol 2003;10:296-7.  Back to cited text no. 4


  [Figure 1], [Figure 2]


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