Tracheobronchopathia osteochondroplastica

Tracheobronchopathia osteochondroplastica is a very rare idiopathic non-neoplastic tracheobronchial abnormality.

Epidemiology

The estimated prevalence on routine bronchoscopy is up to 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 ulceration of a nodule or an acute infection. 

Pathology

Development of osseous and/oror/or cartilaginous 1-8 mm nodules ^2,3in the submucosa of the trachea and bronchial walls. They may be either focal or diffuse. There is characteristic sparing of the posterior membranous portion of the trachea ⁶.

There are two possible theories of pathogenesis ⁵: 

• 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 two-thirds of the trachea and proximal portions of the bronchi ⁴

• only affects the anterior and lateral walls of trachea

Radiographic features

Plain radiograph

Chest radiograph may show irregularity and narrowing of typically affected segments of trachea and bronchi.

CT

• irregular thickening and nodularity of tracheal cartilage, sparing the posterior (membranous) tracheal wall

• small discrete endophytic nodules (typically ~3-8 mm) may be cartilaginous or calcific (ossified)

  • larger nodules may result in luminal narrowing, and should be specifically reported by location and degree of airway narrowing

  • diffuse airway narrowing is not typical

• overall appearance is much more irregular compared to benign cartilage calcification

Treatment and prognosis

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

History and etymology

Initially described in 1857 by Samuel Wilks (1824-1911), as "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.

Differential diagnosis

Imaging differential considerations include:

• tracheobronchial amyloidosis

  • unlike TO, classically circumferential involvement

  • may appear as focal or diffuse narrowing

• relapsing polychondritis

  • like TO, spares posterior membranous tracheal wall

  • more likely smooth, hyperdense mural thickening ¹⁰

  • patients usually have other clinical findings of cartilaginous inflammation ¹⁰