Q: What are the characteristics of the tracheal diverticulum?
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A: Tracheal diverticulum or diverticula are paratracheal air cysts representing an outpouching of the tracheal wall with communication with its lumen. It is a benign and rare entity characterized by single or multiple tracheal wall evaginations, which is frequently an incidental finding. In adults, these diverticula are produced by mucosal herniation through a weak point due to increased intraluminal pressure.
Q: Which are the types of tracheal diverticula?
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A: The tracheal diverticula types are congenital and acquired based on the wall's anatomic location and histological features, with the congenital type being less common. The congenital tracheal diverticula are from respiratory epithelium, smooth muscles, and cartilage. The acquired tracheal diverticula are composed of respiratory epithelium only and lack smooth muscle and cartilage. They are both characterized by single or multiple outpouchings of the tracheal wall, most commonly arising along the trachea's right lateral aspect due to deficient cartilage rings and no esophagus to support the adjacent tissue.
Q: What are the characteristics of the congenital tracheal diverticula?
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A: Congenital tracheal diverticula are usually smaller than the acquired type, and its connection to the trachea is narrow. It is located approximately 4-5 cm below vocal cords or just above the carina. They are more frequent in males than females and are a supernumerary, malformed branch of the trachea. Congenital tracheal diverticula occur due to developmental defects in the tracheal cartilage. The histological structure of this diverticula resembles that of the trachea.
Q: What are the characteristics of the acquired tracheal diverticula?
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A: Acquired tracheal diverticula are usually found in the right posterolateral region of the trachea. It may occur due to a prolonged increase in intraluminal pressure caused by chronic cough and obstructive lung disease (COPD) with emphysema, and also in professions that require excessive vocal cord or pulmonary efforts, leading to an increase in the endoluminal pressure, and consequently, herniation of the mucosa through a weak part in the tracheal wall. Acquired tracheal diverticula are larger than the congenital one, and its wall consists only of respiratory epithelium and devoid of smooth muscle and cartilages. Acquired tracheal diverticula can be single or multiple.
Q: Where is the location of the acquired tracheal diverticula?
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A: The vast majority (97,1%) are at the right posterolateral aspect of the trachea about the thoracic inlet level, between T1 and T3. It projects posteriorly where the cartilage rings are deficient. Usually, it lies to the right, where there is no esophagus supporting the paratracheal tissue compared with the left side. They rarely localize on the left side (2,9%). They appear to have one or multiple direct connections with the trachea and are usually present on CT.
Q: Which are the clinical manifestations of the tracheal diverticula?
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A: Tracheal diverticula are usually asymptomatic and incidentally detected. If secretions fill the cyst, the patient can have dysphagia, odynophagia, painful neck swelling, choking, recurrent episodes of hiccups and burping, hoarseness of voice, chronic cough, dyspnea, stridor, hemoptysis, and recurrent tracheobronchitis. Tracheal diverticula may be a rare cause of difficulty for intubation. Tracheal diverticula can become infected due to recurrent upper respiratory tract infections, and they can progress into a paratracheal abscess.
Q: Which are the associations of tracheal diverticula?
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A: The tracheal diverticula could be a sign of obstructive lung disease (COPD) for acquired type. Multiple acquired tracheal diverticula are the hallmark of tracheobronchomegaly or Mounier-Kuhn disease.
Q: Which is the best imaging method for the diagnosis of tracheal diverticula?
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A: A computed tomographic examination is the best imaging modality for the diagnosis of tracheal diverticula. It can demonstrate the communication channel between the tracheal lumen and the diverticula and the possible damage of the lung's parenchyma due to chronic illness. Bronchoscopy is also useful for the diagnosis of tracheal diverticula. However, sometimes it is not easy to show the connection between the tracheal diverticula and tracheal lumen with bronchoscopy.
Q: How is the treatment of tracheal diverticula?
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A: In most cases, the tracheal diverticula are asymptomatic and need no treatment. Occasionally it may accumulate respiratory secretions that become infected and leading to coughing or tracheobronchitis. In symptomatic cases, conservative measures, such as antibiotics, mucolytics agents, and physiotherapy are proposed, especially in older patients. In some symptomatic patients, treatment options include endoscopic laser cauterization, electrocoagulation, and surgical resection.
Q: Which are the differential diagnosis of tracheal diverticula?
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A: The differential diagnosis of tracheal diverticula are laryngocele, pharyngocele, Zenker diverticulum, apical hernia of the lung, apical paraseptal blebs, or bullae.