Tracheobronchopathia osteochondroplastica

Tracheobronchopathia osteochondroplastica (TO) is a very rare idiopathic non neoplastic tracheo-bronchial abnormality.

Epidemiology

The estimated prevalence on routine bronchoscopy can be upto 0.7% . It typically affects those in the 5^th to 6^th decades and there may be a male predilection ⁴. 

Clinical presentation

Most patients are asymptomatic. Those who have symptoms may present with cough, shortness of breath on exertion, wheezing or recurrent respiratory infection. Haemoptysis can occasionally result from an ulceration of a nodule or an acute infection. 

Pathology

There is development of osseous or cartilaginous 1-8mm ^2-3 nodules or both in the submucosa of the trachea and bronchial walls. They may be either focal or diffuse. There is characterisitic sparing the posterior membranous portions of the trachea ⁶.

There are two possible theories of pathogenesis: 

• ecchondrosis and exostosis from cartilage rings
• cartilaginous and osseous metaplasia of the elastic tissue in the internal elastic fibrous membrane. 

Location

• classically affects the lower 2/3^rds of the trachea and proximal portions of the bronchi ⁴.
• only affects the anterior and lateral walls.

Radiographic features

Chest radiograph

May show irregularity and narrowing of the typically affected segments of the trachea and bronchi.

CT

May additionally show thickened tracheal cartilages with sparing of posterior membranous portions. There are small (typically ~3-8 mm) calcific nodules along its inner tracheal aspect, protruding into the tracheal lumen. The appearance is much more irregular than that seen with normal cartilage calcification.

History and etymology

Initially described in 1857 by SSamuel Wilks in 1857(1824-1911), as ossific"ossific deposits in the larynx, trachea and bronchi" in a 38-year-old-male who died of pulmonary tuberculosis ⁵. The condition was later termed "tracheopathia osteochondroplastica" in 1910 by German pathologist Karl Ludwig Aschoff (1866-1942) 5.

Treatment and prognosis

It is a benign condition and often no interventional in required in asymptomatic cases. Successful recovery with NSAIDS and Dapsonedapsone have been reported in symptomatic cases. Overall prognosis is generally good and is dependent upon airway stenosis caused by nodules.  

Differential diagnosis

Imaging differential considerations include:

• tracheobronchial amyloidosis:  involves the posterior membranous portion of the trachea
• relapsing polychondritis: spares the posterior membranous portion of the trachea