Severe tracheobronchopathia osteochondroplastica in an asymptomatic patient

Abstract

Tracheobronchopathia osteochondroplastica (TO) is a rare condition affecting the lumen of the tracheobronchial tree. It is characterised by the presence of multiple osseous and cartilaginous nodules with posterior wall sparing. While it is a benign condition, it can cause narrowing of the tracheal lumen and subglottis to varying degrees. Approximately 400 cases have been reported worldwide, with an incidence of 0.3% in autopsies and between 1 in 125 and 1 in 5000 on bronchoscopy. As most patients are asymptomatic, this may contribute to underdiagnoses and relative low incidence. Severity of the condition is often unrelated to patient symptomatology. We present a patient with one of the most severe cases of TO seen at our institution. Despite being asymptomatic, significant tracheal and bronchial narrowing was found incidentally on laryngobronchoscopy.

Background

Tracheobronchopathia osteochondroplastica (TO) is a rare condition affecting the lumen of the tracheobronchial tree. It is characterised by the presence of multiple osseous and cartilaginous nodules with posterior wall sparing. While it is a benign condition, it can cause narrowing of the tracheal lumen and subglottis to varying degrees. As most patients are asymptomatic, this may contribute to underdiagnosis. An incidence of 4.2 per 100 000 people, with a mean age of 60 years and equal gender distribution has been reported, although more than 90% of cases are diagnosed on postmortem examination.^{1 2} Severity of the condition is often unrelated to patient symptomatology. We present a patient with one of the most severe cases of TO seen at our institution. Despite being asymptomatic, significant tracheal and bronchial narrowing was found incidentally on laryngobronchoscopy.

Case presentation

We report a case of a woman in her 50s, admitted to our institution for an elective cholecystectomy. The patient had a medical history of gallstones and thalassaemia trait, was a non-smoker and had no known allergies. She had no family history of respiratory diseases and was successfully intubated 13 years ago for a gynaecological procedure. Prior to this admission, there were no reports of cough, dysfunction in breathing or other respiratory symptoms. Preoperative anaesthetic assessment did not identify any airway or respiratory abnormalities and during induction, she was considered a grade 1 in laryngoscopy. Despite this, the anaesthetic team was unable to advance an endotracheal tube past the subglottis. The patient was then ventilated via bag-mask and the procedure was abandoned pending further investigations. A CT of the neck and chest was performed to exclude subglottic stenosis, and this revealed multiple cartilaginous growths arising from the entire cartilaginous surface of the tracheobronchial tree (figure 1). Fibroscopic bronchoscopy evidenced multiple nodules from anterolateral wall of trachea and bronchi protruding into the lumen (figure 2). Biopsies of the lesions taken demonstrated fragments of heterotopic calcification, mature bone and pieces of disorganised cartilaginous tissue.

Figure 1.

(A–C) CT scans showing nodules from tracheal wall and bronchi into air lumen.

Figure 2.

(A, B) Bronchoscopy images demonstrating multiple nodules from anterolateral wall of trachea and bronchi protruding into lumen.

Discussion

TO is a rare, benign condition affecting the lumen of the tracheobronchial tree and characterised by the presence of multiple osseous and cartilaginous nodules, sparing the posterior tracheal wall.³ It was first described by Rotikasky et al in the early 19th century after being noted on an autopsy on a patient with tuberculosis.⁴ Although the pathophysiology behind the formation of these nodules remains unknown, studies have linked TO to defects in bone morphogenetic protein-2, chronic infection with Mycobacterium spp or other bacteria, chronic rhinitis, IgA deficiency and connective tissue diseases.⁵ A study conducted by Tajima et al in 1997 suggested the possible involvement of transforming growth factor-beta 1 in inducing the formation of submucosal osseous and cartilaginous nodules in the tracheobronchial system.⁶ There is no conclusive evidence that genetics or smoking plays a role in TO. Using autopsy and bronchoscopic data, the worldwide incidence of TO is between 0.2% and 0.7%, with a male-to-female ratio of 3:2. TO is typically seen more in elderly patients than in younger patients. The average age of patients with TO is 52 years.⁷ In symptomatic patients, the most common presentations are respiratory. A retrospective review of 15 patients conducted by Nienhuis et al in 1990 showed that 66% presented with cough, 53% with dyspnoea on exertion and 30% with wheeze.⁸ Another study by Jabbardarjani et al showed that chronic dyspnoea was the most common symptom.⁹ Diagnosis of TO is often incidental. While plain radiographs do not show any TO changes, CT scans are useful in the diagnosis and can identify the hallmark ossified nodules measuring 1–10 mm involving the anterolateral wall of the trachea and bronchi.⁴ Direct observation via bronchoscopy remains gold standard to diagnose TO.¹⁰ Typical findings on bronchoscopy include firm, glossy nodules projecting into the lumen of the distal two-thirds of the trachea and proximal main bronchi, causing varying degrees of airway stenosis. Although these nodules are more commonly seen in the distal third of the trachea, involvement of the proximal trachea and larynx has also been demonstrated. When larynx and upper airway are affected, laryngoscopy may be sufficient to establish the diagnosis.¹¹

TO is commonly divided into three categories (scattered, diffuse and confluent) according to the extent of nodular involvement. While in scattered disease there are few nodules with large areas of normal mucosa, diffuse disease presents as widespread nodularity with no normal mucosa visible. Confluent disease presents as widespread nodularity with fusion of adjacent lesions leading to airway compromise from mechanical obstruction.¹²

There is no specific treatment for TO. Laser ablation, surgical resection and stenting are typically reserved for cases of TO with severe airway stenosis.¹³ Medical management using bronchodilators and inhaled corticosteroids has been used in individual case reports; however, the authors speculate that this was to treat underlying lung disease and support mucociliary clearance and would be unlikely to influence the underlying pathophysiology of the disease.^{5 6} Aims of treatment should be to restore airway patency through lasering any larger obstructing lesions. Silicone stenting can be placed endoscopically to create temporary intraluminal compression of the lesions.¹¹ Respiratory infections and underlying lung disease should be managed in a timely and aggressive manner. A focused airway plan for the patient should be documented and in case of difficult intubation, a medical bracelet detailing this should be worn. In patients who develop recurrent cough and chest infections, antibiotics and antitussives play a key role in the management of TO.¹⁴

Learning points.

• Tracheobronchopathia osteochondroplastica is a widely underdiagnosed condition and it is often diagnosed incidentally.

• Bronchoscopy is essential for both diagnosis and to isolate pathogens in recurrent infections.

• When diagnosed, aim of treatment should be to restore patency through lasering obstructing lesions.

Ethics statements

Patient consent for publication

Obtained.