Lecture 16: ILD Flashcards
what are the Interstitial lung diseases?
- -A heterogeneous group of lung disorders marked by inflammatory changes in the alveoli. ILDs can be idiopathic or due to secondary causes such as autoimmune disease, or exposure to drugs or toxic substances.
- -Multitude of diseases that cause FIBROSIS of the pulmonary parenchyma/interstitium, resulting in restrictive defect on pulmonary function.
examples of ILDs?
- -Pneumoconiosis
1) Inhaled organic and inorganic dust
2) Hypersensitivity pneumonitis - -Fibrosis associated with connective tissue disorders
1) SLE, rheumatoid arthritis, scleroderma, dermatomyositis - -Sarcoidosis
- -Idiopathic pulmonary fibrosis (i.e unknown etiology)
- -Drugs (eg Bleomycin, Radiation, etc)
ILDs cause obstructive or restrictive patterns?
restrictive
what is the interstitial space?
The interstitial space is defined as loose connective tissue throughout the lung (alveolar walls and septae)
what are the 3 subdivisions of the interstitial space of lung?
1) Bronchovascular: the area surrounding the bronchi, arteries, and veins from the root of the lung to the respiratory bronchiole
2) Parenchymal: situated between the alveolar and capillary basement membranes
3) Subpleural: situated beneath the pleura, as well as the interlobular septae
how ILD is diagnosed?
Interstitial lung disease is diagnosed by a combination of radiographic features in combination with clinical signs and symptoms, but can be diagnostically and therapeutically challenging!!
does interstitial space is visible radiographically?
The interstitium of the lung is not normally visible radiographically; it only becomes visible when it involved in a disease process, which increases its volume and attenuation.
what is the hallmark of ILDs?
Hallmark of this disease is FIBROSIS or SCARRING
what is the result of fibrosis and scarring in the lungs?
As the alveolar walls become fibrotic and scarred, diffusion of oxygen and carbon dioxide is impaired, resulting in lack of oxygen transfer to blood, causing hypoxaemia and dyspnoea.
what is the most common ILD?
- -Idiopathic pulmonary fibrosis (IPF): most common
- -Risk factors: cigarette smoking, environmental or occupational exposures, chronic aspiration, genetic predisposition
what are the occupational, environmental, and iatrogenic causes of ILD?
1) Pneumoconioses
- -Asbestosis
- -Silicosis
- -Rare pneumoconioses (e.g., berylliosis, anthracosis)
2) Radiation pneumonitis
what medications can cause lung fibrosis?
–Chemotherapeutic agents: bleomycin , methotrexate, busulfan
Other agents: amiodarone , nitrofurantoin, phenytoin, –penicillamine, cocaine, and heroin
what are the bleomycin and busulfan?
1) A metal-chelating, glycopeptide antibiotic that has a cytotoxic effect on nondividing tumor cells by causing fragmentation of DNA chains. Used to treat lymphomas, germ cell tumors, head and neck cancers, and squamous cell carcinoma. Adverse effects include fever, hypersensitivity reactions, skin changes, and severe pulmonary fibrosis.
2) An alkylating chemotherapeutic agent of the alkyl sulfonate class. Often used in bone marrow ablation prior to transplantation for chronic lymphocytic leukemia. Common adverse effects include severe myelosuppression, electrolyte imbalance, hyperpigmentation, cardiac, pulmonary, and hepatic toxicity.
what are the ILDs secondary to underlying disease?
1) Granulomatous ILD:
- -Sarcoidosis: noncaseating granulomas in multiple organs, including the lung
- -Pulmonary Langerhans cell histiocytosis
- -Granulomatosis with polyangiitis (formerly Wegener granulomatosis)
- -Eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss syndrome)
2) Infectious diseases (eg, tuberculosis, legionellosis)
3) Alveolar filling disease
4) Hypersensitivity reactions ( hypersensitivity pneumonitis and eosinophilic pneumonitis)
5) Connective tissue disorders
6) Bronchoalveolar carcinoma
the alveolar filling disease includes…
Includes Goodpasture’s syndrome, idiopathic pulmonary hemosiderosis, and pulmonary alveolar proteinosis (rare condition caused by accumulation of surfactant-like protein and phospholipids in alveoli)
what CTDs can cause ILDs?
rheumatoid arthritis, scleroderma, systemic lupus erythematosus, and mixed connective tissue disease
how ILDs are classified?
1) Etiology
2) Radiology
- -Based on zones of fibrosis
- -Upper, mid, lower, widespread
3) Histology
what are the ILDs that predominantly involve upper lung zones?
- -Sarcoidosis
- -Langerhans cell Histiocytosis
- -Coal workers pneumoconiosis
- -Ankylosing spondylitis
- -Radiation
- -Silicosis
what are the ILDs that predominantly involve lung mid zones?
- -TB
- -Chronic EAA
what are the ILDs that predominantly involve lung lower zones?
- -Rheumatoid arthritis
- -Asbestosis
- -IPF
- -Drugs
- -Scleroderma
- -Collagen vascular disease
what are the pneumoconioses?
A group of restrictive interstitial lung diseases caused by the inhalation of certain dust, often affecting miners and agricultural workers. Asbestosis and silicosis are the most common types.
inorganic vs organic pneumoconioses?
1) Inorganic (mineral dust pneumoconioses)
- -Asbestosis, silicosis, coal, Beryllium
2) Organic
- -Extrinsic allergic alveolitis/hypersensitivity pneumonitis
- -Mouldy hay, bird feces, cotton fibers
In ILD, large particles (>10 mcm) are deposited in terminal bronchioles, alveolar ducts, and alveoli and result in fibrosis and granuloma formation. T/F
False Small particles (<10mcm)
what are the factors of particles that influence pathogenicity?
- -Size
- -Shape
- -Chemical composition
- -Concentration
- -Solubility
- -Particle reactivity
- -Duration of exposure
- -Co-existence of other lung diseases
Particles1-5um may reach alveoli – most dangerous size
Particles >5-10um are unlikely to reach distal alveoli
<0.5um tend to act like gases and move into and out of alveoli without causing damage
Shape - > Long and thin eg asbestos
how particle size and shape influence ILD pathogenicity?
- -Particles1-5um may reach alveoli – most dangerous size
- -Particles >5-10um are unlikely to reach distal alveoli
- -<0.5um tend to act like gases and move into and out of alveoli without causing damage
- -Shape - > Long and thin eg asbestos
5-10 mcm size particles are the most dangerous. T/F
False
particles 1-5um may reach alveoli – most dangerous size
what is the coal worker’s pneumoconiosis?
A severe form of anthracosis that occurs with prolonged exposure to coal and carbon dust. Characterized by nodular opacities (typically <1 cm) in the upper lobes of the lung and chronic bronchitis that can progress to pulmonary fibrosis.
- -Anthracosis: heterogeneous pulmonary infiltrates, with/without mass lesion
- -Coal workers’ pneumoconiosis: fine nodular opacifications (< 1 cm) in upper lung zone
who is at risk for acquiring coal workers pneumoconiosis?
- -City dwellers
- -Coal miners
what are the characteristic features of coal worker’s pneumoconiosis?
1) Milder than other types of pneumoconiosis
2) Pulmonary fibrosis rarely occurs.
3) Coal workers’ pneumoconiosis (also known as black lung disease or black lung):
- -A more severe form of anthracosis
- -Occurs only with prolonged exposure to large amounts of coal
- -Carbon-laden macrophages induce inflammation
- -Characterized by chronic bronchitis that progresses to progressive massive pulmonary fibrosis
coal worker’s pneumoconiosis affects upper or lower lung zones?
upper
what is the silicosis?
Silicosis is a common occupational lung disease that is caused by the inhalation of crystalline silica dust.
who is at increased risk for silicosis?
- -Workers that are involved for example in construction, mining, or glass production are among the individuals with the highest risk of developing the condition.
- -Sand blasting, quarrying, mining, stone cutting, foundry work, ceramics
what occupational group is at risk of acquiring asbestosis?
Mining, milling, fabrication of ores and materials, installation and removal of insulation
what occupational group is at risk of acquiring berylliosis?
Nuclear energy and aircraft industries
what causes lung injury inpneumoconioses
Inhalation of inorganic dust – especially chronic, occupational exposure – causes an inflammatory reaction in the lung parenchyma
- -FIBROGENIC FACTORS (TNF, PDGF)
- -PROINFLAMMATORY FACTORS (LTB4, IL-8, IL-6)
- -TOXIC FACTORS (proteases, ROS)
what is the spectrum of disease of coal worker’s pneumoconiosis?
1)Pulmonary anthracosis
–Most innocuous coal induced pulmonary lesion
–Commonly seen in urban dwellers and smokers
Inhaled carbon pigments taken up by alveolar macrophages, accumulate in connective tissue along lymphatics and in lymph nodes
2)Simple coal workers’ pneumoconiosis (CWP)
3)Complicated CWP
4)Caplan syndrome
what is Caplan syndrome?
Caplan syndrome (pneumoconiosis in combination with rheumatoid arthritis) → rapid development of basilar nodules and mild obstruction of ventilation
what are the features of simple coal workers’ pneumoconiosis (CWP)?
- -Focal dust accumulation around respiratory bronchioles
- -Characterised by coal macules and larger coal nodules
- -Macules consist of dust-laden macrophages
- -Nodules are a collection of collagen fibers
- -Upper zone predominant
- -Can eventually cause dilatation of alveoli leading to centrilobular emphysema
- -Usually not functionally disabling
what are the microscopic lesions of coal workers pneumoconiosis?
Microscopically the lesions consist of dense collagen and pigment, often with central necrosis due to ischemia
what are the features of complicated coal worker’s pneumoconiosis?
- -Also called Progressive Massive Fibrosis (PMF)
- -Develops after 10-20 years
- -Occurs on a background of simple CWP by coalescence of the coal nodules
- -Intensely black scars; usually multiply
- -Microscopically the lesions consist of dense collagen and pigment, often with central necrosis due to ischemia
- -Upper zone predominant
- -Massive confluent fibrosis
- -Minority of cases lead to increasing pulmonary dysfunction, pulmonary hypertension, and cor pulmonale
- -Progression of CWP to PMF linked to coal dust exposure level and total dust burden
progression of CWP to PMF depends on…
coal dust exposure level and total dust burden
what are the complications of CWP?
Minority of cases lead to increasing pulmonary dysfunction, pulmonary hypertension, and cor pulmonale
Caplan syndrome occurs with what pneumoconioses?
- -This syndrome also occurs in asbestosis and silicosis
- -Definition: Co-existence of rheumatoid arthritis with pneumoconiosis leading to the development of distinctive nodular pulmonary lesions that develop fairly rapidly
- -Nodules exhibit central necrosis surrounded by palisading fibroblasts, plasma cells, macrophages containing coal dust and collagen
nodules in Caplan syndrome are composed of…
Nodules exhibit central necrosis surrounded by pallisading fibroblasts, plasma cells, macrophages containing coal dust and collagen
amorphous silica is the most dangerous. T/F
False
Silica occurs in crystalline and amorphous forms, but crystalline forms (quartz, cristobalite, tridymite) are more toxic and fibrogenic