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
Symptoms of idiopathic UIP, Risk factors and treatment
- dypsnoea, cough, basal crackles, cyanosis, clubbing
- death within 5yrs
- Restrictive PFT + GT
- pathology=UIP
- elderly >50 M>F
- CXR
- steroids
What is seen on CXR in Idiopathic UIP?
- basal/posterior fibrosis with honeycombing ( complicated by peripheral adenocarcinoma)
- diffuse infiltrates, cysts, ground glass appearance of pulmonary fibrosis
What is honeycombing of lungs?
is the radiological appearance seen with widespread fibrosis. Presence of small cystic spaces with irregularly thickened walls composed of fibrous tissue.
