Pathology of restrictive lung dieseases Flashcards
What is restrictive lung disease
- group of pulmonary and extra pulmonary diseases characterised by reduced lung compliance, hence decreased lung volumes.
Features of intersitial lung disease
- FEV1 + FVC reduced (VC is a key marker)
- FEV1:FVC ratio normal
- V/Q imbalance when small airways affected
- reduced gas transfer ( Tco or Kco) < diffusion abnormality
Types of restrictive lung diseases/condition
- Interstitial lung disease
- muscoskeletal
- pleura
- subdiaphragmatic
Name Intersitial lung diseases
-diffuse alveolar damage, sarcoidosis, hypersensitivity pmeumonitis, idiopathic pulmonary fibrosis
State Muscoskeletal conditions ( restrictive)
- -amytrophic lateral sclerosis, thoracoplasty, ankylosing spondylitis, kyphoscoliosis, rib fractures
State restrictive pleural conditions
-pleural effusion, pneumothorax, pleural thickenings
State subdiaphragmatic restrictive conditions
-obesity( prevents diaphragm descending), pregnancy
What is the lung intersitium
- microscopic space that forms part of the BBB
- connective tissue found around airways + space inbetween basement membranes of alveolar walls
Patterns of diffuse intersitial lung disease
Acute: Diffuse alveolar damage(DAD)
Granulomatous responses(C): Sarcoidosis, Hypersensitivity pneumonitis
Usual Intersitial pneumonitis(C): Cryptogenic fibrosing alveolitis, Idiopathic pulmonary fibrosis(IPF), Connective tissue diseases, Drugs, Asbestos, viruses
Other(C): Non-specific(NSIP), asbestos, sillicosis, COP, BOOP, cmoking related fibrosis
What is diffuse alveolar damage?(DAD) and state the causes
- acute response to intersitial damage
- major trauma, chemical injury/toxic inhalation, circulating shock, drugs, infection, radiation, autoimmune disease
- can be idiopathic ( without known cause)
Describe stages of DAD
-Exudative and proliferative
- protein rich oedema formed and fills alveoli, the basement membrane of alveoli also shed in alveolar lumen.
- Fibrin deposition ( formation of hyaline membrane) which is a fibrous layer that settles in alveoli preventing GE
- epithelial cells proliferation occurs
- fibroblast proliferation occurs
- widespread fibrosis in air spaces + intersitium follows
- patients may die of secondary infection/underlying cause of DAD opposed tos carring itself
What is sarcoidosis?
- multisystem granulomatous disorder of unknown cause
- disease of temperature climates
- affects F>M
Histopathology of sarcoidosis
- non caseous granuloma ( no necrosis)
- epitheloid + giant cell granulomas
- little lymphoid infiltrate
- variable associated fibrosis
What organs does sarcoidosis affect?
- Lymph nodes
- Lung
- Spleen
- Liver
- Skin, eyes, skeletal muscle
- Bone marrow
- Salivary glands
(all arranged from most common)
Symptoms of sarcoidosis
- Acute arthralgia(YA) [resolves after 2 years]
- Erythema nodosum(YA) [resolves after 2 years]
- Bilateral hilar lymphadenopathy (YA)[resolves after 2 years]
- SOB, cough, abnormal CXR[resolve/persist/progress]
- asymptomatic[resolve/persist/progress]
Treatment of sarcoidosis
-corticosteroids
Investigations of sarcoidosis
- Hypercalcaemia ( serum Calcium ions)
- High ACE enzyme
- hypergammaalbuinaemia(high gamma globin)
- Kveim test 60% +ve (historical int)
- Tuberculin test (historical int)
What is hypersensitivity pneumonitis
- inflammation of alveoli due to exposure of organic dust
Antigens of hypersensitivity pneumonitis
-thermophillic actinomycetes (Micropolyspora faeni,
Thermoactinomyces vulgaris> farmers lung)
- bird/animal proteins ( faeces, bloom)
- fungi(aspergillus)
- chemicals
Acute presentation of Hyper sensitivity pneumonitis (extrinsic allergy alveolitis)
ACUTE
- fever
- dry cough
- myalgia
- chills 4-9hrs after ag exposure
- crackles, tachyopnoea, wheeze
- precipitating antibody
CHRONIC
- insidious
- malaise, SOB, cough
- low grade illness
- crackles, some wheeze
Can lead to RF as Gas transfer is low. History is important !
Histopathology of hypersensitivity pneumonitis
Type 3/4 hypersensitivity reaction ( immune complexes + Th1 cells)
- soft centriacinar epitheloid granuloma
- interstitial pneumonitis
- foamy histiocytes
- bronchiolitis obliterans
- upper zone disease
Where can intersitial pneumonitis be seen in?
- connective tissue diseases (sleceroderma + rheumatoid disease)
- drug reaction
- post infection
- industrial exposure( asbestos)
-most is Cryptogenic(cryptogenic fibrosing alveolitis)/idiopathic(idiopathic pulmonary fibrosis)
What is usual intersitial pneumonitis
-progressive scarring of both lungs. The scarring (fibrosis) involves the supporting framework (interstitium) of the lung.
Histopathology of UIP
- patchy intersitial chronic inflammation
- type 2 pneumocyte hyperplasia
- smooth muscle + vascular proliferation
- Evidence of old/recent injury - temporal + spatial heterogeneity
- proliferating fibroblastic foci
