Pathology of Restrictive Lung Disease 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 is in direct contact in normal alveolar walls
Most of the alveolar epithelial (pneumocyte) and interstitial capillary endothelial cell basement membranes
What can enter the alveolar wall space in restrictive lung diseases
Inflammatory cells, fibroblasts and collagen
What does the presence of inflammatory cells, fibroblasts and collagen in the alveolar wall space cause
Increased diffusion distance of air
What do inflammatory cells, fibroblasts and collagen in the alveolar wall develop into and what does this cause
Fibrosis causing the lungs to become stiff due to an increase in the amount of elastic tissue and reduction in stretch ability due to the excess components present in the alveoli wall
What are the 4 main features of restrictive lung diseases
Reduced lung compliance (stiff lungs)
Low FEV1 and FVC but FEV1/FVC ratio is normal
Reduced gas transfer (Tco or Kco) – diffusion abnormality
Ventilation/perfusion imbalance – when small airways are affected by pathology
Why is there a reduction in FEV1 and FVC
Because there is a lung volume reduction
Do restrictive lung diseases have air flow limitation
No
How can gas transfer be measured
By the movement of CO that is breathed in in a single breath and can be measured in the blood to calculate the transfer of CO from air to the blood
How much V/Q imbalance is seen in some restrictive lung diseases
Small amount
How are diffuse lung diseases normally found
Abnormal CXR
How will diffuse lung diseases present
Dyspnoea
Type 1 respiratory failure leading to heart failure
Is the dyspnoea found in diffuse lung disease upon exertion or at rest
Upon exertion but as the disease progresses it will be present at rest also
How many ribs will be seen on a chest X-Ray of interstitial lung disease
Less than 10 with more markings between the ribs
Where is the site of inflammation in interstitial lung disease
Parenchymal
What type of inflammation can parenchymal lung injury cause
Acute or Chronic
How many pathways does chronic inflammation have. Name them
3
Usual interstitial pneumonitis (UIP)
Granulomatous responses
Other patterns
What do all of the chronic inflammation pathways lead to
Fibrosis or End-stage Honeycomb Lung
What can end stage pulmonary fibrosis lead to
Respiratory failure
Which process is most likely to lead to end stage pulmonary fibrosis
UIP
Which process is least likely to lead to end stage pulmonary fibrosis
Granulomatous response
Give an example of acute inflammation due to parenchymal lung injury
Diffuse Alveolar Damage DAD
What is DAD associated with
Major trauma Chemical injury / toxic inhalation Circulatory shock Drugs Infection Auto(immune) disease Radiation But it can be idiopathic
What does DAD cause
A large leak in the capillaries of the alveolar walls
The damage to the capillaries is most likely mediated by neutrophil polymorphs
What do some patients with DAD present with
Severe respiratory failure and admitted straight to ITU
Over 50%
Where is fibrosis found in DAD
Interstitial space and alveoli walls
What are the histological features of DADS
Protein rich oedema Fibrin Hyaline membranes Denuded basement membranes Epithelial proliferation Fibroblast proliferation Scarring - interstitium and airspaces
Why is proliferation seen in DADS
To try and repair the damage caused
What is the fluid and protein found in DADS transformed to
Fibrous tissue which forms a solid lung
What can a granulomatous response cause
Sarcoidosis
Hypersensitivity pneumonitis
What is sarcoidosis
A multisystem granulomatous disorder of unknown atiology
What are the characteristic features of sarcoidosis in histopathology
Epithelioid and giant cell granulomas
Necrosis/caseation very unusual
Little lymphoid infiltrate
Variable associated fibrosis
Can sarcoidosis lead to fibrosis
Yes but unlikely to lead to end-stage fibrosis
Who is commonly affected by sarcoidosis
Young adults
Females more than males
What is the incidence of sarcoidosis in the UK
3-4/100,000
What is the incidence of sarcoidosis in Afro-Americans the USA
20/100,000
What will a young adult with sarcoidosis show
Acute arthralgia
Erythema nodosum
Bilateral hilar lymphadenopathy
Can sarcoidosis be discovered when there are no symptoms
Yes in an incidental abnormal CXR
May resolve, persist or progress
What else can patients with sarcoidosis present with
SOB
Cough
Abnormal CXR
May resolve, persist or progress
Do young patients presenting with acute arthralgia, erythema nodosum and bilateral hilar lymphadenopathy require treatment
No
It is a self-limiting condition which resolves within 2 years
How is sarcoidosis treated with
Corticosteroids
What 4 things can be used to diagnose sarcoidosis
Clinical findings
Imaging findings
Elevated serum Ca++ and ACE
Biopsy
What is hypersensitivity pneumonitis
A reaction to inhaled antigens (normally of organic origin)
Name some type of antigens which can cause hypersensitivity pneumonitis
Thermophilic actinomycetes (e.g. Micropolyspora faeni, Thermoactinomyces vulgaris) Bird/Animal proteins - faeces, bloom Fungi - Aspergillus spp Chemicals Others
What do you see in the acute presentation of hypersensitivity pneumonitis
Fever, dry cough, myalgia,
Chills 4-9 hours after antigen exposure
Crackles, tachyopnoea, wheeze
Precipitating antibody
What do you see in the chronic presentation of hypersensitivity pneumonitis
Insidious
Malaise, SOB, cough
Low grade illness
Crackles and some wheeze
What is one of the most important aspects when seeing a patient with suspected hypersensitivity pneumonitis
History
Is acute or chronic hypersensitivity pneumonitis seen more often
Chronic
What type of hypersensitivity reaction is hypersensitivity pneumonitis
Immune complex mediated
Type III and type IV hypersensitivity reaction
What can hypersensitivity pneumonitis lead to
Soft centriacinar epithelioid granulomata
Interstitial pneumonitis
Foamy histiocytes
Bronchiolitis obliterans
Which part of the lung does hypersensitivity pneumonitis affect
Upper Zone
