Large And Small Airway Disease Flashcards
Features of emphysema on CXR
Flattening and inversion of diaphragm Diaphragm below seventh rib Depletion of blood vessels Reduced transverse cardiac diameter
Difference between smoking related and alpha 1 anti trypsin deficiency emphysema.
Smoking - centrilobular apical Alpha 1 Antitrypsin - panacinar basal
Specific dimensions of CXR lung hyperinflation
Height > 29.9cm right lung Flat hemidiaphragm (perpendicular distance from costo to cardio phrenic angles < 1.5cm) Apex of right hemidiaphragm below 7th rib Narrow transverse diameter of heart
Definition of a Bullae
Area of emphysema greater than 1cm. Wall thickness less than 1mm
Three forms of emphysema
Centriacinar Panacinar Para septal
Two forms of centriacinar emphysema
Centrilobular. Smokers. Upper lobe. Focal. Coal and mineral dust exposure
Features of panacinar emphysema
Alpha 1 Antitrypsin def Lower lobe predominance. Uniform. affects entire acinar Diffuse
Features of para septal emphysema
Affects distal acinar segment. Large Bullae Sub pleural. Upper lobe mainly
Features of paracicatrical emphysema
Irregular emphysema Around areas of fibrosis, scarring
With large Bulla what should you noted for the clinician
Quality of adjacent lung as will guide surgical management
In preassesment of lung surgery what should you note in the report
Any: Pleural disease Bronchiectasis Pulmonary nodules Dilated pulmonary artery Calcified pulmonary artery
Common caused of tracheal stenosis
External Goitre Fibrosing mediastinitis Intrinsic Focal e.g. tracheal stricture Diffuse e.g. amyloid
Appearances of Goitre induced tracheal stenosis on CXR
Goitre is a common condition and therefore a relatively common cause of tracheal narrowing. The cause is usually a benign multinodular goitre. The appearance on plain film is: Paratracheal mass - the location is variable Smooth eccentric tracheal narrowing
What is fibrosising mediastinitis
This is a rare condition, where fibrous tissue encases the mediastinal structures. It is a progressive condition that can affect the trachea and main bronchi by narrowing and compressing them. Obstructive complications can occur, secondary to the compression.
Causes of tracheal strictures
Tracheal stricture is usually caused by a traumatic insult to the trachea. One of the commonest causes is tracheal intubation and tracheostomy.
Other causes include:
Radiotherapy
Surgery
Burns
Idiopathic
Features of fibrosing mediastinitis on CT
soft tissue is seen replacing mediastinal fat. There may also be calcifications. There is abnormal soft tissue replacing the mediastinal fat.
The differential diagnosis is malignancy.
Appearances of tracheal stenosis on CT due to intubation
Circumferential narrowing over approximately 2 cm
A thin membrane or diaphragm, caused by granulation tissue
A long, thickened eccentric stenosis, usually caused by the tip of the tube
Tracheomalacia, caused by thinning of the cartilage (usually due to pressure necrosis or infection), or removal of cartilage at tracheostomy
What is tracheobronchomalacia
Tracheobronchomalacia is a weakness of the tracheal or bronchial walls and the supporting cartilage. This leads to easy collapsibility. It can be a focal or a diffuse process.
Side effect of Tracheobronchomalacia
The malacia causes an ineffective cough, which will cause mucous retention leading to infections and bronchiectasis. Patients may also present with stridor and shortness of breath.
Causes of tracheobronchomalacia
There are many causes:
Post intubation
Thyroid lesions
Trauma
Infection
Radiotherapy
Relapsing polychondritis
Primary condition - most often seen in children
CT appearances of a benign tracheal neoplasm
Well-circumscribed round soft tissue mass
Smaller than 2 cm
Sessile or polypoidal
No extension beyond the wall of the trachea
Most common causes of malignant tracheal neoplasm
Squamous cell carcinoma is the most common malignancy, accounting for 50% of cases. It is four times more common in men.
Adenoid cystic carcinoma is the second commonest malignancy. It is equally common in men and women and has no relationship to smoking. It usually involves the posterolateral wall of the mid to lower trachea.
Other malignant tracheal tumours include:
Carcinoid (usually bronchial, enhance avidly and may contain calcifications), mucoepidermoid tumours
Lymphoma
Leukaemia
Plasmacytoma
Appearances of Malignant Tracheal Neoplasm on CT
Focal or circumferential narrowing
Flat or polypoidal mass
2-4 cm
May extend beyond the tracheal wall
Adjacent lymph nodes
Tracheoeosophageal fistula
How may metastatic lesions cause tracheal or bronchial stenosis
Metastases may involve the airway either by:
Haematogenous spread
Local invasion
Haematogenous metastases have been described with melanoma, breast, colon, genito-urinary and renal tumours. They present as an endoluminal mass
Local invasion may occur from:
Thyroid tumours
Oesophageal tumours
Laryngeal tumours
Lung tumours
Complications of Paliative Stenting of Airways
Stent migration
Airway erosion
Stent fracture
Distal lung collapse
Intrinsic Diffuse Conditions causing Tracheal Stenosis
Amyloid
Relapsing polychondritis
Sabre-sheath trachea
Tracheobronchopathia osteochondroplastica
Tuberculosis
Wegener’s granulomatosis
Features of Amyloid induced Laryngotracheobronchial Malacia
Amyloidosis is characterised by the extra-cellular deposition of fibrillar proteins, resistant to proteolysis. This material stains red with Congo red, showing apple-green birefringence under polarised light.
Laryngotracheobronchial amyloidosis is a form of localised pulmonary amyloidosis, it usually presents in middle-age and is twice as common in men as women. Symptoms are those of bronchial obstruction or haemoptysis.
CT features of Laryngotracheobronchial amyloidosis
Appearance on CT includes:
Diffuse or focal deposits causing stenoses
The stenoses may be concentric or eccentric
Calcifications are common
The posterior membrane of the trachea is spared
Lung or segmental collapse
Features of Relapsing Polychondritis
Relapsing polychondritis is a rare systemic disease that affects cartilage throughout the body. It is believed to be an auto-immune disorder and the condition is characterised by the progressive replacement of the cartilage by fibrous tissue.
It usually presents in middle-age and equally effects men and women, although airway complications are commoner in females.
The respiratory system is involved in 50-70% of cases and the complications (usually recurrent pneumonia) lead to 50% of deaths.
Features of relapsing polychondritis induced airway stenosis on CT
Inflammation and swelling of the glottic and sub glottic area is the commonest appearance
Diffuse or focal cicatricial contraction occurs late - there will be circumferential narrowing of the trachea and main bronchi
The tracheal wall may have some calcifications
The posterior membrane is usually spared
Tracheomalacia can occur
Features of Sabre-sheath Trachea and location
This condition has a strong association with chronic obstructive pulmonary disease and lung hyperinflation. It may occasionally be seen with mediastinal lipomatosis.
It is commoner in adult males. The whole length of the intrathoracic trachea is involved and it may occasionally lead to tracheomalacia.
The diagnosis is made when the coronal diameter of the trachea is less than half the sagittal diameter – usually they are roughly equal. The cartilage rings may be calcified but are not thickened.
Features of TB associated Airways stenosis
Airway stenosis is now rare following the introduction of antibiotic treatment. It is usually the distal trachea and main bronchi that are affected by an initial inflammatory process that heals with fibrosis and stricturing.
Bronchial obstruction can occur due to broncholithiasis.
This can be a complication of calcified lymph nodes, usually secondary to tuberculosis, sarcoidosis or silicosis
The calcified node compresses an adjacent airway or erodes into it, leading to bronchial obstruction
In the right middle lobe this is often referred to as the ‘right middle lobe syndrome’
Features of Wegener’s Granulomatosis airway stenosis
Appearance on CT includes:
Subglottic stenoses that may involve the vocal cords (Fig 1)
Inflammatory pseudotumours
The tracheal rings can be thickened and calcify
Stenoses of the trachea and bronchi
Secondary lung collapse
