Lecture 11.0 - Restrictive Lung Disease Notes Flashcards
Name the 2 sites where the causes of interstitial fibrosis mostly occur in the lung
- At the lower lung
- Sparing of the lower lung/lung bases (occur not in these regions)
Name the causes of interstitial fibrosis occuring at the lower lung
- Organising DAD
- Acute interstitial fibrosis (Hamman-Rich)
- Chronic idiopathic pulmonary fibrosis:
a.Primary
b.Secondary - ie with systemic disease (ie rheumatoid arthritis, systemic sclerosis) - Chronic oedema
- Asbestosis
Name the causes of interstitial fibrosis sparing the lower lung
- Sarcoidosis
- Extrinsic allergic alveolitis /
hypersensitivity pneumonia - Silicosis
- Chronic berylliosis
- Infections with a granulomatous pattern
(may involve the whole lung, ie TB)
What are the 2 clinical presentations of DAD?
- Hypoxia (low oxygen levels)
- Bilateral lung opacities on chest imaging
ALI / ARDS / DAD (Diffused Alveolar Damage)
Same disease process just different names used in different departments
PATHOGENESIS OF ADA:
Name the 2 stages of ADA
- Early / exudative
○ Endothelial activation
○ Adhesion and extravasation of neutrophils
○ Accumulation of intra-alveolar fluid and formation of hyaline
membranes - Organising / proliferative
-Type 2 pneumocyte hyperplasia
-Increase of fibroblasts and myofibroblasts within the alveoli wall
- Interstitial inflammation and fibrosis
● Chronic or fibrotic stage which resolves the injury
PATHOLOGIC FINDINGS OF DAD:
What are the expected findings of DAD macroscopically?
Heavy, firm, red, boggy lung
What are the characteristics of DAD survivors?
Survivors:
- Recover, some may have persistent impairment in cognitive and physical function
- Chronic lung disease : scarring, interstitial fibrosis, end stage/honeycomb lung
Restrictive Lung Diseases are classified according to the anatomical occassion that is affected. What 2 anatomical occassions are normally affected on RLD?
- Chest wall disorders
These include:
-Neuromuscular diseases
incases of-
○ Poliomyelitis
○ Severe obesity
○ Pleural disease
○ Kyphoscoliosis - Chronic diffuse ‘interstitial diseases’ of the lung parachyma
These include:
-Fibrosing diseases
○ Granulomatous disorders
○ Smoking-related interstitial diseases
○ Other:
■Langerhans cell histiocytosis
■Pulmonary alveolar proteinosis
■Lymphoid interstitial pneumonia
PATHOLOGIC FINDINGS OF DAD:
What are the expected findings of DAD microscopically?
Early stage:
- Congestion
- Interstitial and intra-alveolar oedema
- Fibrin deposition
- Waxy hyaline membranes
- Fibrin-rich oedema fluid
- Cytoplasmic and lipid remnants of necrotic epithelial cells
Organising stage:
- Proliferation of type II pneumocytes
- Granulation tissue in alveolar walls and spaces
- Fibrous scarring may occur, not always
* May have superimposed bronchopneumonia
What do the patients hospitalized for DAD normaly present with?
Patients usually hospitalised for ALI:
- Dyspnoea, tachypnoea, cyanosis, hypoxaemia, respiratory failure
- Radiology : diffuse bilateral infiltrates
- Ventilation required : V/Q mismatch (uneven distribution of injured lung, some unaerated and collapsed, other regions almost normal), respiratory acidosis
Name the conditions or disoders that fall under fibrosing diseases
● Usual interstitial pneumonia
● Non-specific interstitial pneumonia
● Cryptogenic organising pneumonia
● Connective tissue disease-associated
● Pneumoconiosis
○Silicosis
○Asbestosis
○Coal workers pneumoconiosis
● Drug reactions
● Radiation pneumonia
What is pneumoconiosis?
● Non-neoplastic lung reaction to mineral dusts, particulates, chemical fumes and vapours in the workplace
● It is an occupational lung disease
● Examples of mineral dusts:
○ Silica - gold miners, stone workers, sandblasters
○ Asbestos : asbestos mines, ship builders, insulation, electrical work
○ Coal
Discuss the pathogenesis of pneumoconiosis
- Amount of dust retained in lung and airways
a. Dust concentration duration of exposure, effectiveness of clearing mechanisms - Size, shape and buoyancy of the particles
a. Most dangerous particles : 1 -5 μm in diameter - Particle solubility and physiochemical properties
a. Small particles of high solubility may cause rapid onset lung damage
b. Larger particles may resist dissolution - Possible additional effects of other irritants
a. Tobacco smoke
What is silicosis?
Common lung disease caused by inhalation of silica (crystallin silicon dioxide)
What is the site mostly affected by silicosis?
Upper lobes of the lung field
Name 2 forms of silica
- Amorphous ((quartz,cristobalite,tridymite)
- Crystallline (silica particles with the capacity to cause fibrosis)
What is the macroscopic and microscopic finding of silicosis?
-macroscopic: Tiny white nodules (+black if coal
dust present) on lung surface
- microscopic: Silicotic nodule/islet = concentric layers of hyalinized collagen surrounded by dense capsule of more condensed collagen
Discuss the timeline of silicosis presentation following exposure
- Presents after decades of exposure, or
- occasionally as acute (accelerated or rapid) silicosis with heavy exposure for a few months to years.
What is a life threatening disease associated with silica?
Associated with increased susceptibility to TB (due to effect of silica on pulmonary macrophages)
-Inhaled silica particles are phagocytosed by macrophages
○Activation of inflammatory mediators (Il-1 and IL-18)
Differs from other inorganic dusts as it has oncogenic properties
asbestosis
- Tiny white nodules (+black if coal dust present) in upper zones of lungs
- May undergo central softening and
cavitation (superimposed
TB/ischemia) - Evolves to progressive massive fibrosis (PMF), area of scarring >1cm
- Fibrotic lesions may occur in hilar lymph nodes and pleura
Pathology of silicosis
What are the 2 forms of asbestos?
● Serpentine
○Curly and flexible
○More common type
● Amphibole
○Straight, stiff and brittle
○More pathogenic due to aerodynamic properties and
solubility
Discuss the pathology of asbestos-related disease
● Diffuse pulmonary interstitial fibrosis with asbestos bodies
● Fibrosis
○ Begins in lower lobes / bases and sub-pleurally
○ Fibrosis distorts lung architecture, eventual honeycomb-lung
● Asbestos bodies
○ Golden-brown, fusiform/beaded rods with a translucent center
○ Consist of asbestos fibers coated with an iron-containing proteinaceous material
