Pathology of Restrictive Lung Diseases Flashcards
What is the interstitium of the lung?
The connective space around the airways and vessels. Also the space between the basement membranes of the alveolar walls
What are the effects of interstitial lung disease on FEV1 and FVC?
Low FEV1
Low FVC
Ratio is normal
What happens to lung compliance in restrictive lung disease?
Reduced so stiff lungs
What happens to gas transfer in restrictive lung disease?
Reduced due to diffusion abnormality
Is the main cause of hypoxia
What happens to ventilation/perfusion in restrictive lung disease?
There is a ventilation/perfusion imbalance when small airways affected by pathology
What is the presentation of restrictive lung disease?
Dyspnoea on exertion and at rest when disease progresses
Discovery of abnormal CXR or CT scan
What can restrictive lung disease lead to?
Respiratory failure type 1
Heart failure
What is the signs of restrictive lung disease on CXR?
Reduced lung volume and increased lung markings
What is the acute response to parenchymal lung injury?
Diffuse Alveolar Damage (DAD) or known as ARDS or shock lung
What is diffuse alveolar damage associated to?
Major trauma, chemical injury, circulatory shock, drugs, infection, autoimmune disease and radiation
Idiopathic
What viruses is diffuse alveolar damage associated to?
Influenza
SARS Cov1
SARS Cov2
Explain the evolution of DADs
It is a modified acute inflammatory response
There is involvement of immune tissue damage
Has exudative and proliferation stage
What are the histological features of DADs?
Protein rich oedema, fibrin, hyaline membranes and denuded basement membranes
Alveoli is filled with fluid and surrounded by proteins with fibrin making gas exchange harder
What type of proliferation occurs in DADs?
Epithelial and fibroblast
What is the result of DADs histologically?
Scarring of interstitium and airspaces so gives solid lung
What are some chronic responses to parenchymal lung injury?
Usual interstitial pneumonitis (UIP), granulomatous responses and other patterns
What is sarcoidosis?
A multisystem granulomatous disorder of unknow aetiology
What is the histopathology of sarcoidosis?
Epithelioid and giant cell granulomas
Necrosis/ caseation is very unusual
Little lymphoid infiltrate and variable associated fibrosis
What is the presentation of sarcoidosis?
Young adult - acute arthralgia, erythema nodosum and bilateral hilar lymphadenopathy
SOB, cough and abnormal CXR
What is the treatment for sarcoidosis?
Most resolve after 2 years
Some may resolve, persist or progress so may need corticosteroids
What is used to diagnose a patient with sarcoidosis?
Clinical findings, imaging findings, serum Ca++ and ACE, and biopsy
What is hypersensitivity pneumonitis?
Patient is exposed to sensitive antigen by inhalation
Is due to immunological makeup
What can cause hypersensitivity pneumonitis?
Thermophilic actinomycetes, bird/ animal proteins, fungi, chemical and others
What is the presentation of acute hypersensitivity pneumonitis?
Fever, dry cough and myalgia
Chills after exposure
Crackles, tachypnoea and wheeze
What are the presentation for chronic hypersensitivity pneumonitis?
Insidious - not aware of antigen exposure
Malaise, SOB and cough
Low grade illness
Crackles and wheeze
Explain the histopathology of hypersensitivity pneumonitis?
Soft centriacinar epithelioid granulomata
Foamy histocytes, interstitial pneumonitis and lymphocytes around granuloma
What immune complex mediated reactions happen in hypersensitivity pneumonitis?
Type 3 and 4
3 - chronic inflammation
4 - granulomas
What zone does hypersensitivity pneumonitis usually effect?
Upper zone disease - where the fibrosis usually seen
What is a usual interstitial pneumonitis UIP?
Idiopathic Pulmonary Fibrosis
Which chronic response has the most chance of end stage honeycomb lung/ fibrosis?
Usual interstitial pneumonitis UIP
When might usual interstitial pneumonitis be seen?
Connective tissue diseases, drug reaction, post infection and industrial exposure - asbestos
Most are idiopathic
Explain the histopathology of UIP?
Patchy interstitial chronic inflammation and type 2 pneumocyte hyperplasia
Smooth muscle and vascular proliferation
Fibroblastic Foci
What is temporal and spatial heterogenicity of UIP?
Temporal - can see all stages of lung in different places
Spatial - some affected and some of lung not
What is the clinic presentation of idiopathic pulmonary fibrosis?
Dyspnoea, cough
Basal crackles, cyanosis and clubbing
What is the prognosis for idiopathic pulmonary fibrosis?
Some are steroid responsive
Poor prognosis as irreversible
What is seen on the lung when a patient has UIP?
Basal and posterior fibrosis with honeycombing
What is the risk of fibrotic conditions?
Causing lung cancer
