Tracheobronchopathia osteochondroplastica: a cause of chronic cough and haemoptysis

Abstract

Tracheobronchopathia osteochondroplastica (TPO) is a rare disorder of the tracheopulmonary tree characterised by osseous and cartilaginous submucosal nodules projecting into the tracheal lumen, sparing the posterior tracheal membranous wall. Symptoms are non-specific and may include dry cough, hoarseness, dyspnoea, recurrent pneumonia and occasionally haemoptysis. A fibreoptic bronchoscopy showing multiple tracheal nodules followed by pathological biopsy is required to reach the final diagnosis. Here, we report two cases of TPO, both with history of biomass fuel exposure and almost similar clinical presentions with chronic cough, shortness of breath and intermittent haemoptysis. They both underwent fibreoptic bronchoscopy showing multiple tracheal nodules whose histopathological analysis showed the diagnosis of TPO. Both patients were treated conservatively and remained in good health afterwards. Physicians should be aware about the need of advanced surgical procedures including endotracheal stent placement in more severe cases.

Background

Tracheobronchopathia osteochondroplastica (TPO) is a rare benign disorder of the trachea which occasionally also involves the main bronchi. TPO was first identified in 1855 by Rokitansky,¹ and later in 1857, Wilks² provided the first microscopic description of the disease as ossific deposits in the larynx, trachea and bronchi. The diagnosis is usually preceded by symptoms of chronic cough,³ wheezing,⁴ dyspnoea and haemoptysis.⁵ There have been instances where the diagnosis was picked up incidentally while performing routine bronchoscopy for workup of metastatic disease,⁶ during difficult intubation⁷ and chest X-ray abnormality.⁸ It has also been reported as a complication of laryngeal tuberculosis.⁹ The disease usually becomes evident on bronchoscopy and can further be established on a biopsy. This disease has not been reported frequently, which could be due to misdiagnosis, lack of knowledge and ignorance of the disease. A diagnosis of TPO should be kept in mind when patients present with chronic unresolved cough and haemoptysis. Here, we report two cases where the patients were diagnosed with TPO after bronchoscopy and histopathology. Both of these patients also had history of biomass fuel exposure for many years and anthracosis visible on bronchoscopy.

Case presentation

Case 1

A 61-year-old Asian woman, housewife, with history of biomass fuel exposure, presented to the clinic with the complaints of productive cough and shortness of breath on exertion for the last 8 months. She reported three episodes of haemoptysis in the last 6 months, the most recent being 1 month ago. It was fresh blood and about two teaspoons in quantity. She also complained of intermittent fever for 1 month. The fever was undocumented but was subjectively described as ‘low grade’. She also gave a history of biomass fuel exposure by cooking food on wood fire and burning of coal to keep the house warm in winters for many years. She denied any weight loss or decrease in appetite. There was no history of tuberculosis contact. Her medical and surgical history was unremarkable.

On her physical examination, she was found to be afebrile, her blood pressure was 118/86 mm Hg, the pulse was 88 beats/min and her respiratory rate was 24 breaths/min. She had bilateral expiratory wheeze on auscultation. The rest of her physical examination was unremarkable.

Case 2

A 48-year-old Asian woman, housewife, presented to the clinic with history of productive cough and shortness of breath on exertion for the last 3 years, with worsening of symptoms for the last 2 months. She complained of low-grade, intermittent fever for 2 weeks. She complained of two to three episodes of haemoptysis with small amount of blood-tinged sputum in the last 1 month. There was no associated chest pain. The patient denied any loss of appetite and weight loss. She also gave a significant history of biomass fuel exposure for the last 20 years.

On her physical examination, she was vitally stable and afebrile. She had inspiratory stridor with bilateral wheeze on auscultation. The rest of her physical examination was unremarkable.

Investigations

Case 1

On admission, complete blood count was normal as were her renal and liver function tests. A chest X-ray was done which showed nodular infiltrates bilaterally with alveolar infiltrates in the right lower zone (figure 1). A high resolution computed tomography (HRCT) scan of chest was done which revealed bilateral nodular infiltrates in lung parenchyma with irregular and calcified trachea (figure 2). A bronchoscopy was hence done to look for any apparent source of haemoptysis. The bronchoscopy revealed extensive nodular changes involving the whole trachea sparing the posterior part and main bronchi (figure 3). Patchy areas of blackish pigmentation of airways suggestive of anthracosis were also seen in the right and left upper lobes. Bronchoalveolar lavage was sent for microbiology and cytology. The microbiology results yielded growth of Pseudomonas aeruginosa. Multiple biopsies were taken from the hard nodular lesions in trachea and were sent for histopathological examination.

Figure 1.

Chest X-ray showing bilateral reticulonodular infiltrates with atelectasis in the right middle lobe.

Figure 2.

Longitudinal sections of CT scan of the chest showing irregular-beaded appearance of trachea with small nodules in bilateral lung zones.

Figure 3.

Bronchoscopic view showing diffuse nodular lesions in trachea sparing posterior tracheal wall.

The histolopathology revealed bronchial tissue fragments covered by pseudostratified ciliated columnar epithelium and the underlying subepithelial tissue showed calcified bony spicules (figure 4). Based on the history, radiological and histopathological findings, diagnosis of TPO was made. The lung findings were consistent with bronchial anthracosis as suggested by long-standing exposure to biomass fuel and evidence of blackish pigmentation of airways on bronchoscopy; radiological findings were also suggestive of bronchial anthracosis.¹⁰

Figure 4.

Histological examination of biopsy of tracheal nodules showing presence of calcified tissue beneath the surface epithelium, a characteristic histological feature of tracheobronchopathia osteochondroplastica.

Case 2

The laboratory investigations including complete blood count, renal and liver functions were normal. Chest X-ray showed fibrotic bands in the right upper lobe. A fibreoptic bronchoscopy was then planned to look for the cause of her symptoms which showed multiple nodules involving the tracheal lumen with sparing of the posterior wall, anthracotic patches were also seen mainly involving the right upper lobe (figure 5). Bronchoalveolar lavage was sent for microbiology, while endotracheal biopsies were taken from these hard nodules. Bacterial cultures showed growth of Staphylococcus aureus, while the rest of cultures including fungal and Mycobacterium tuberculosis showed no growth.

Figure 5.

Bronchoscopy showing multiple small, rounded nodules in the tracheal lumen with sparing of posterior tracheal wall. Anthracosis was also seen in the right upper lobe.

The histopathological examination of the biopsied tissue showed bronchial epithelial hyperplasia, squamous metaplasia and bone formation (figure 6). TPO was considered as the cause of chronic cough.

Figure 6.

Histological examination of tracheal nodules of second case showing calcified tissue.

The lung findings were again suggestive of bronchial anthracosis as the patient had prolonged biomass fuel exposure with evidence of blackish pigmentation of airways suggestive of anthracosis. Further research should be done to find a probable causal relationship between bronchial anthracosis or anthracofibrosis and TPO.

Differential diagnosis

Both cases had almost similar presentations of chronic cough, shortness of breath and intermittent hemoptysis with bronchoscopic findings of multiple tracheal nodules suggestive of endotracheal tuberculosis, papillomatosis, tracheobronchial amyloidosis and tracheal tumours as our differential diagnoses. The bronchoscopic cultures were negative for tuberculosis, and the histopathological results did not reveal presence of tumour, amyloidosis or features of human papillomavirus.

Treatment

Case 1

The patient was started on ciprofloxacin for 1o days to treat Pseudomonas aeruginosa. The patient was counselled about her disease. She was advised to avoid biomass fuel exposure. Spirometry was not done due to financial constraints but the patient was started on budesonide-formeterol inhaler considering chronic obstructive pulmonary disease (COPD) as a likely cause of her recurrent wheezing in chest with a positive history of long-standing exposure to biomass fuel and was vaccinated with influenza and pneumococcal vaccines.

Case 2

The patient was given supportive treatment with tranexamic acid for 3 days to treat haemoptysis, levofloxacin for Staphylococcus aureus infection for 1 week and tiotropium bromide 18 mcg inhaler again considering COPD developing after prolonged biomass fuel exposure leading to recurrent wheezing episodes as evident on clinical examination. Later, she was vaccinated with influenza and pneumococcal vaccines.

Outcome and follow-up

Case 1

The patient responded well to treatment and has not experienced any worsening of her respiratory symptoms for the last 8 months.

Case 2

The patient had two episodes of small amount of haemoptysis in the last 6 months. The rest of her symptoms including cough and shortness of breath improved with the medications.

Discussion

TPO is a rare benign disease that affects the trachea and, to a lesser extent, the main bronchi. The aetiology remains unclear, although several hypotheses have been formulated like acquired connective tissue metaplasia, cartilaginous ring exostoses, ossification of elastic cartilage, reactive inflammation secondary to chronic infections (eg, Mycobacterium tuberculosis), metabolic abnormalities (eg, amyloidosis) and genetic predisposition.^11–13 Both our patients had history of significant biomass fuel exposure with anthracosis seen on bronchoscopy, suggesting a possible association with this entity. The disease is caused by the formation of cartilaginous or bony nodules that project into the lumen of the airway, with sparing of the posterior wall.¹⁴ It has no gender predominance and no clear association with smoking.¹⁵ Patients are usually asymptomatic initially, but later can have symptoms like chronic cough, hoarseness, wheezing, haemoptysis and dyspnoea.¹⁶

Chest radiographs are usually normal, but may show tracheal irregularity, pulmonary infiltrates or lobar collapse as a manifestation of recurrent infections due to lack of pulmonary toilet as the cartilaginous projections may cause atelectasis and mucus plugging. Both of our patients had similar complications. Advance imaging such a CT scan may demonstrate multiple submucosal calcified nodules involving the anterior and lateral walls of the tracheobronchial tree with sparing of the posterior tracheal wall.¹⁷

The bronchoscopic findings are quite characteristic which usually shows hard whitish spicules, deriving from both the anterior and the lateral tracheal wall, which project into the tracheal lumen, while the main bronchi and larynx are less often affected. Both of our patients showed a similar pattern. Differential diagnosis of TPO includes tracheobronchial amyloidosis, granulomatosis with polyangiitis, endobronchial sarcoidosis, tuberculosis, papillomatosis, and bronchial and tracheal wall tumours. Hence, a biopsy helps in further establishment of the diagnosis, although it is difficult to obtain due to the firm nature of the spicules. Histopathological analysis usually depicts osseous and cartilaginous growth within a calcified protein matrix, protruding into the bronchial lumen growths. Adipose tissue fragments, along with foci of bone marrow with active haematopoiesis, can also be seen.¹⁸

There is no definitive treatment for TPO. Supportive treatment includes antibiotics for recurrent infections, mechanically removing obstructing nodules via cryotherapy, laser excision, segmental tracheal resection and endotracheal stent placement.^19–21

Patient’s perspective.

Case 1: “I was worried about my disease and blood in sputum and though it could be TB or cancer, but after undergoing bronchoscopy, it was smooth and after biopsy came, I was somewhat relieved. Now I am taking medicines regularly and doing better”.

Case 2: “I am feeling better now and breathing is improving with medicines. I still have cough and sputum but better”.

Learning points.

• Tracheobronchopathia osteochondroplastica (TPO) is a rare, benign entity that is often diagnosed incidentally while performing bronchoscopy.

• Physicians should have adequate awareness to recognise this disease and avoid unnecessary investigations.

• Only supportive treatment is required in majority of patients like antibiotics for recurrent infections and bronchodilators with pneumococcal and influenza vaccinations.

• For severe cases, patients may require surgical procedures like mechanically removing obstructive nodules or endotracheal stent placement.