Tracheal Diverticulum

A tracheal diverticulum is a small air filled outpouching from the wall of the trachea. It is found in about 1 to 4% of adults on CT and is usually an incidental finding.

The congenital form (tracheal bronchus like or paratracheal air cyst) lies on the right posterolateral wall at the level of the thoracic inlet, within 4 to 5 cm of the vocal cords, often communicating with the trachea through a narrow neck. The acquired form is from herniation of mucosa through a weak wall after chronic cough or in diseases such as COPD, and occurs in the lower trachea.

Pathophysiology. Congenital forms arise from a failure of normal tracheal wall development or a rudimentary tracheal bronchus. Acquired forms arise from raised intratracheal pressure with weakness of the membranous wall. The narrow neck traps secretions, which can lead to infection.

Most patients have no symptoms. Others have chronic cough, recurrent infection, a sensation of neck fullness, hoarseness, dysphagia or dyspnoea. Difficulty with intubation or a tube cuff entering the sac can occur, and a tracheal diverticulum may be found when imaging for another reason.

Stridor, haemoptysis or signs of neck infection need prompt assessment.

• CT of the neck and chest: air filled paratracheal cavity with a narrow channel to the trachea, usually on the right at the T1 to T3 level.
• Flexible bronchoscopy to show the orifice, which can be difficult to find, and to exclude other airway disease.
• Barium swallow if the oesophagus is a possible source of symptoms.

Differential diagnosis.

• Laryngocele
• Oesophageal (Zenker) diverticulum
• Apical lung bulla or paratracheal air cyst of another origin
• Thyroid cyst
• Tracheobronchial fistula

• Asymptomatic, found by chance: reassurance, no treatment and no routine follow up.
• Infection of the sac: amoxicillin-clavulanate 625 mg three times daily for 7 days (reduce to 625 mg every 12 hours at eGFR 10 to 30), with doxycycline 100 mg twice daily in penicillin allergy. Chest physiotherapy and mucolytic drug such as carbocisteine 750 mg three times daily.
• Persisting or recurrent symptoms: surgical excision through a cervical approach, or endoscopic obliteration of the neck by laser or electrocautery in selected cases. Surgery carries a risk of recurrent laryngeal nerve injury and tracheal fistula.
• Anaesthesia: record the finding in the notes, use fibreoptic intubation techniques and avoid positioning the cuff in the sac.
• Treat chronic cough or underlying lung disease that may cause enlargement.

Monitoring. No routine monitoring for asymptomatic cases. After surgery, review at 6 weeks with clinical review and imaging if symptoms recur.

Referral and escalation. Refer to ENT or thoracic surgery for recurrent infection or compressive symptoms.