Tracheal diverticulum is a rare anomaly involving the tracheobronchial tree. Tracheal diverticulum was first described by Rokitansky in 1838.4 The overall prevalence of tracheal diverticulum is approximately 1% according to an autopsy series by MacKinnon.5 It could be either congenital or acquired in origin, though most are congenital. Congenital tracheal diverticuli develop from the vestigial structure of supernumerary lung and are usually associated with other congenital malformations such as tracheoesophageal fistula (TEF).6 They could also be secondary to herniation of tracheal mucosal membrane through an inherent muscular defect.
Acquired lesions are usually sequelae of TEF repair.7 Multiple acquired tracheal diverticula are the hallmark of tracheobronchomegaly or Mounier-Khun disease.8 They may appear at any level, although they are more common in the posterolateral region, between the extrathoracic and intrathoracic trachea.
Tracheal diverticula may present in multiple forms. It has been described with stasis of secretions occurring within the diverticulum leading to chronic aspiration and pulmonary infections; persistent cough, which may be the consequence of the diverticulum or direct stimulation of the vagal nerve; associated with severe tracheomalacia and airway obstruction when the tip of the endotracheal tube is displaced in to the diverticulum. Multiple tracheal diverticuli have not been reported in cases of CF. A series of symptomatic tracheal diverticula reveals that patients may develop respiratory symptoms as late as 11 years after distal TEF repair.
Here, we present a case of multiple tracheal diverticuli in a CF patient who may represent either an associated congenital anomaly or an acquired complication of the disease.
The possibility of acquired type may be higher in this case as CF with chronic cough raises intraluminal pressure inside the trachea, which eventually leads to herniation of the mucosa at the weakest points, commonly in the posterior wall which is devoid of cartilaginous rings.8,9 Other mechanism that might have contributed to diverticuli formation is the exaggerated inflammatory response in these patients. Bacterial infection is the direct mechanism of airway inflammation in CF. Bronchoalveolar lavage of these patients shows increased concentration of neutrophils and interleukin-8 and decreased anti-inflammatory factors. Airway inflammation in CF is also postulated to be an exaggerated inflammatory response though tumor necrosis factor-κβ dysregulation.9 Moreover, inflammation leads to high levels of active matrix metalloproteases-9 and neutrophil elastase, which are capable of digesting elastin and fibronectin leading to marked weakness of the airway, which could lead to diverticuli formation.10
Another point, which also favors the acquired origin in this case, is the absence of cartilage that usually surrounds the congenital diverticuli. Another difference between both types is the width of the opening of the diverticulum; wide opening is common with the acquired type,11 even though this was not the situation in our case.
The diagnosis of the tracheal diverticulum should be suspected from the presence of air in the paratracheal region. With helical CT acquisition, the exact origin and extension of the pouch can be determined, being even superior to bronchoscopy, which may miss it if the diverticulum has a narrow opening.11
The clinical significance of the tracheal diverticulum lies in the fact that it may be a reservoir of infection. Caution should be practiced during endotracheal intubation in patients with large tracheal diverticulum as it can be inadvertently intubated, leading to perforation. Ching reported a case in which independent lung ventilation using double lumen endotracheal tube was cumbersome due to the presence of a tracheal diverticulum.11
The treatment of the diverticulum depends upon its presentation and may vary from close observation to surgical resection. In most symptomatic patients, chest physiotherapy, antibiotics, and mucolytic agents could be sufficient. In severe cases of acquired tracheal pouches after a repair of TEF, endoscopic management can be used. The endoscopic approach includes cauterization with laser or electrocoagulation or endoscopic division of the redundant flap using microlaryngeal scissors.7
We have reported a case of multiple tracheal diverticuli in a patient with CF. We suspect they were acquired in origin. We doubt their contribution to the recurrent infections, as there was no evidence of air fluid levels or tracheal discharge from the tracheal opening.
1. Cheung JC, Deber CM. Misfolding of the cystic fibrosis
transmembrane conductance regulator and disease. Biochemistry. 2008;47:1465–1473.
2. Donaldson SH, Boucher RC. Sodium channels and cystic fibrosis
. Chest. 2007;132:1631–1636.
3. Wolf K, Mathur P, Busk M, et al. Multiple acquired tracheal diverticula. J Bronchol. 1996;3:43–46.
4. Frenkiel S, Assimes IK, Rosales JK. Congenital tracheal diverticulum. A case report. Ann Otol Rhinol Laryngol. 1980;89(5 Pt 1):406–408.
5. Mackinnon D. Tracheal diverticula. J Pathol Bacteriol. 1953;65:513–517.
6. Restrepo S, Villamil MA, Rojas IC, et al. Association of two respiratory congenital anomalies: tracheal diverticulum and cystic adenomatoid malformation of the lung. Pediatr Radiol. 2004;34:263–266.
7. Johnson LB, Cotton RT, Rutter MJ. Management of symptomatic tracheal pouches. Int J Pediatr Otorhinolaryngol. 2007;71:527–531.
8. Early EK, Bothwell MR. Congenital tracheal diverticulum. Otolaryngol Head Neck Surg. 2002;127:119–121.
9. Elizur A, Cannon CL, Ferkol TW. Airway inflammation in cystic fibrosis
. Chest. 2008;133:489–495.
10. Kelly E, Greene CM, McElvaney NG. Targeting neutrophil elastase in cystic fibrosis
. Expert Opin Ther Targets. 2008;12:145–157.
11. Soto-Hurtado EJ, Penuela-Ruiz L, Rivera-San Chez I, et al. Tracheal diverticulum: a review of the literature. Lung. 2006;184:303–307.
Keywords:© 2008 Lippincott Williams & Wilkins, Inc.
tracheal diverticuli; cystic fibrosis