Restrictive Lung Disease - Pathology Flashcards
What is the interstitium of the lung?
The connective tissue space around the airways and vessels, and the space between the basement membranes of the alveolar walls.
What are the arrangement of cells in a normal alveolar wall?
Most of the alveolar epithelial and interstitial capillary endothelial cell basement membranes are in direct contact.
What are the signs of interstitial lung disease?
Reduced lung compliance - stiff lungs.
Low FEV1 and FVC, but normal FEV1/FVC.
Reduced gas transfer (Tco and Kco) - diffusion abnormality.
V/Q imbalance - small airways affected.
What is the presentation for diffuse lung disease?
Abnormal CXR or CT.
Presents with dyspnoea.
SOB on exertion (and at rest as the disease progresses).
Respiratory failure (Type I).
Heart failure.
What is the evolution of DAD?
Oedema - first few days.
Increased hyaline membrane production.
Proliferation - interstitial inflammation and interstitial fibrosis occurs, after a week.
What is DAD associated with?
Major trauma.
Chemical injury / toxic inhalation.
Circulatory shock.
Drugs.
Infection (viral - influenza, COVID-19).
Autoimmune disease.
Radiation.
Idiopathy.
What are the histological features of DAD?
Protein rich oedema.
Fibrin.
Hyaline membranes.
Denuded basement membranes.
Epithelial and fibroblast proliferation.
Scarring of interstitium and airspaces.
What is the histopathology of sarcoidosis?
Epithelioid and giant cell granulomas.
Necrosis and caseation (very unusual).
Little lymphoid infiltrate.
Variable associated fibrosis.
What is the incidence of sarcoidosis?
Common in young adults (F>M).
Higher in African-Americans.
Low in equatorial regions.
A disease of temperate climates.
What organs are involved in sarcoidosis?
Lymph nodes - ~100%.
Lung - >90%.
Spleen - 75%.
Liver - 70%.
Skin / eyes / skeletal muscle - 50%.
Bone marrow - 20%.
Salivary glands - up to 50%.
What is the typical presentation of sarcoidosis?
A young adult with acute arthralgia, erythema nodosum, and bilateral hilar lymphadenopathy.
Incidental abnormal CXR or CT.
SOB and cough.
What is the progression and treatment of sarcoidosis?
Resolves after 2 years.
Symptoms may persist or progress.
Treatment - corticosteroids.
What does lymph node sarcoidosis cause?
Non-caseating epithelioid granulomas.
What is the diagnosis of sarcoidosis?
Clinical and imaging findings.
Serum Ca++ and ACE.
Biopsy.
For historical interest -
Kveim test (~60% +ve).
Tuberculin test.
What are the antigens responsible for HP?
Thermophilic actinomycetes.
Bird and animal proteins (faeces, bloom).
Aspergillus spp.
Chemicals.
What is the acute presentation of HP?
Fever, dry cough, myalgia.
Chills.
Crackles, tachypnoea, wheeze.
What is the chronic presentation of HP?
Insidious.
Malaise, SOB, cough.
Low grade illness.
Crackles and some wheeze.
What is the progression of HP?
Respiratory failure.
Low gas transfer.
What is the histopathology of HP?
Type III and IV hypersensitivity.
Soft centriacinar epithelioid granulomata.
Interstitial pneumonitis.
Foamy histiocytes.
Bronchiolitis obliterans.
Upper zone disease.
What are the causes of UIP?
CT diseases (scleroderma, rheumatoid disease).
Drug reaction.
Post infection.
Asbestos.
Idiopathic - IPF, CFA.
What is the histopathology of UIP?
Patchy interstitial chronic inflammation.
Type II pneumocyte hyperplasia.
Smooth muscle and vascular proliferation.
Evidence of old and recent injury.
Proliferating fibroblastic foci.
What is IPF, and its signs and symptoms?
Pathology - UIP.
Typically affects >50yr olds (M>F).
Signs - basal crackles, cyanosis, clubbing.
Symptoms - dyspnoea, cough, restrictive PFTs, reduced gas transfer.
What are the CXR findings, progression, and prognosis of IPF?
CXR - basal/posterior, diffuse infiltrates, cysts, ‘ground glass’.
Progression - most dead in 5 years.
Prognosis - some fulminant / steroid responsive.
What are the chronic responses to interstitial lung injury?
UIP - IPF, CFA, CT diseases, drugs, asbestos, viruses.
Granulomatous responses - sarcoidosis, HP.
Other responses - NSIP, COP, smoking-related fibrosis, asbestos, silicosis.
All result in fibrosis or end-stage honeycomb lung.
What does end-stage lung fibrosis cause?
Hypoxia, SOB, and fatigue.
Limits physical activity.
