Pathology of restrictive lung disease Flashcards
What is the interstitium ?
The connective tissue space around the airways and vessels and the space between the basement membrane of the alveolar walls
What is the relationship between the normal alveolar wall and most of the alveolar epithelial (pneumocyte) & interstitial capillary endothelial cell basement membranes ?
They are in direct contact
What are the characteristics of Restrictive – Diffuse - Interstitial Lung Disease ?
Reduced lung compliance:
- stiff lungs
Low FEV1 & low FVC but FEV1/FVC normal ratio
Reduced gas transfer (Tco or Kco):
- diffusion abnormality
Ventilation/perfusion imbalance:
- when small airways affected by pathology
Is there airflow limitation in restrictive lung disease ?
No
What are the clinical presentations for restrictive lung disease ?
Discovery of abnormal CXR or CT scan
Dyspnoea:
- SOB on exertion
- SOB at rest
Respiratory failure- type 1
Heart failureWhat are the outcomes of Parenchymal (Interstitial) Lung Injury ?
Acute inflammation (can develop into chronic response in rare circumstances) or Chronic inflammation
What is DAD ?
Diffuse alveolar damage
What is DAD associated with ?
Major trauma
Chemical injury/ toxic inhalation
Circulatory shock
Drugs
Infection including viruses:
- influenza
- SARS COV2
Autoimmune disease
Radiation
But it can be idiopathicWhat are the exudative stages of DADS ?
Oedema and Hyaline membranes
Oedema - Vessels become massively leaky - more so than in a normal response
Hyaline membranes - lots of proteins
What are the histological features of DADS ?
Protein rich oedema Fibrin Hyaline membranes Denuded basement membranes Epithelial proliferation Fibroblast proliferation Scarring- interstitium and airspaces
What is the commonest interstitial lung disease that you will encounter ?
Sarcoidosis
What is sarcoidosis ?
A multisystem granulomatous disorder of unknown aetiology
What pathology does sarcoidosis have ?
That of a type 4 hypersensitivity reaction -> granuloma
What is the histopathology of sarcoidosis ?
Epithelioid and giant cell granulomas
Necrosis/ caseation very unusual
Little lymphoid infiltrate
Variable associated fibrosis
What is the presentation of sarcoidosis ?
Young adults
- Acute arthralgia
- erythema nodosum
- Bilateral hilar lymphodenopathy
Incidental abnormal CXR or CT scan- no symptoms
SOB, cough and abnormal CXRDo most patients with sarcoidosis reach end stage fibrotic lung disease ?
No
What is the diagnosis of sarcoidosis ?
Clinical findings
Imaging findings
Serum, Ca++ and ACE
Biopsy
What are the hypersensitivity pneumonitis antigens ?
Thermophilic actinomycetes
- micropolyspora faeni
- thermoactinomyces vulgaris
Bird/ animal proteins- faeces, bloom
Fungi- aspergillus spp
Chemicals
OthersWhat is the acute presentation for Hypersensitivity Pneumonitis ?
Fever, dry cough, myalgia
Chills 4-9 hours after Ag exposure
Crackles, tachypnoea, wheeze
Precipitating antibody
What is the chronic presentation of hypersensitivity pneumonitis ?
Insidious Malaise, SOB, cough Low grade illness Crackles and some wheeze (Can lead to respiratory failure Gas transfer low History important)
What type of hypersensitivity causes Hypersensitivity Pneumonitis ?
Immune complex mediated combined Type III and Type IV Hypersensitivity reaction
What is the histopathology of hypersensitivity pneumonitis ?
Soft centiacinar epitheliod granulomata Interstitial pneumonitis
Foamy histiocytes
Bronchiolitis obliterans
Upper zone disease
What are the causes of Usual interstitial pneumonitis ?
Connective tissue diseases - scleroderma and rheumatoid disease
Drug reaction
Industrial exposure
Idiopathic/cryptogenic reasons
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:
- temporal heterogenicity
- spatial heterogenicity
Proliferating fibroblastic fociWhat are Proliferating Fibroblastic Foci ?
Nodules of fibrous tissue in the walls of the alveoli, reflect the severity of the disease
Who usually suffers from Idiopathic Pulmonary Fibrosis ?
Elderly >50
M>F
What is the clinical presentation of Idiopathic Pulmonary Fibrosis ?
Dyspnoea, cough
Basal crackles, cyanosis, clubbing
What is the prognosis for Idiopathic Pulmonary Fibrosis ?
Poor prognosis
Usually dead within 5 years
What will you see in the chest X-ray for someone with Idiopathic Pulmonary Fibrosis ?
Basal/posterior, diffuse infiltrates, cysts, ‘ground glass’
What is UIP Basal and posterior fibrosis with honeycombing often complicated with ?
Peripheral adenocarcinoma
Describe the airway flow in interstitial lung disease ?
Normal air flow, diffusion is altered
