T2 L13: Restrictive lung diseases: fibrosis

Cards (42)

  • What is the interstitium of the lung?
    spaces in lungs between and around air sacs
    includes:
    • connective tissue (ie basement membrane)
    • patrolling immune cells and fibroblasts
    • blood and lymphatic vasculatures
  • What is intralobular septa?
    connective tissue
    surround alveoli
    thin layer between alveoli and capillaries
  • What is interlobular septa?
    outline secondary lobules
    contain lymphatics and veins of lungs
    only visible on CT when thickened from disease
  • What is peri-bronchial interstitium?
    supports the thin terminal + respiratory bronchiole walls
  • What is a secondary lobule?
    smallest functional unit in the lung that:
    • contains a central artery and a terminal bronchiole
    • is bound by a fibrous connective tissue
  • What are interstitial lung diseases (ILDs)?
    diseases that cause inflammation or scarring
    starts at one of these locations:
    • intralobular / interlobular septa
    • respiratory bronchioles
    • capillary endothelial cells (vasculitis)
  • What is the goal in ILD care?
    to make a specific diagnosis
    as many symptoms are non-specific (eg dyspnoea, cough, restriction, hypoxaemia)
  • What is the difference in granulomas in tuberculosis vs ILD?
    in ILD little to no necrosis in granulomas
  • What are granulomas?

    collection of macrophages, typically with lymphocytes in the outer rim
  • What are nodules?
    lumps due to inflammation
    lymphatic distribution - along interlobar septa
    centrilobular distribution - do not touch fissures
  • What are reticulations and ground glass opacities and how do they arise?
    seen on CT
    reticulations: fine lines
    ground glass opacities: fuzzy grey patches (due to air / fluid / fibrosis)
    manifest due to infiltration of lymphocytes along the intralobular septa (ie around alveoli)
  • What is 'peribronchial infiltrate of lymphocytes'?
    areas of lymphocytes around air trapping
    occurs when air can't be adequately exhaled
    also where small bronchioles have congested and narrowed lumens
  • What are 'collagen plugs'?
    collagen plug and inflammation in alveoli and around respiratory bronchioles
    cause 'consolidations': alveoli filled with inflammatory cells and collagen
  • What are 'fibroblast foci'?
    collections of fibroblasts that make scarring collagen
    get activated permanently
    can't discrete on imaging
  • What are fibrotic reticulations?
    fine lines formed from scarring in the intra-alveolar septal spaces
  • What are honeycomb cysts?
    fibroblast foci create fibrosis
    which destroy normal lung tissue
    ultimately results in honeycomb cysts
  • Terms related to inflammation
    granuloma
    nodules
    intralobular infiltrate of lymphocytes
    peribronchial infiltrate of lymphocytes
    collagen plugs
  • Terms related to fibrosis
    fibroblast foci
    reticulations
    honeycomb cysts
  • What is 'Non-specific interstitial pneumonia (NSIP)'?
    infiltration of lymphocytes along intralobular septa
  • What is 'Organizing pneumonia' (OP)?
    plugs of collagen and inflammation in alveolar and respiratory bronchioles
  • What is 'Usual interstitial pneumonia (UIP)?
    disease pattern
    includes fibroblast foci with tails of fibrosis
  • What are the 3 pathology patterns?
    NSIP pattern (intralobular septa)
    Organizing pneumonia pattern (in alveoli)
    UIP pattern (fibroblast foci)
  • What is Hypersensitive Pneumonitis?
    chronic inflammatory disease that can convert to fibrosis
    (less common: chronic HP - high antigen exposure, flu-like illness)
    causes: exposure to organic dust + genetic predisposition
    symptoms: shortness of breath, cough, wheeze
  • How does hypersensitive pneumonitis show on imaging?
    nodules, granulomas, ground glass opacities
  • How is hypersensitive pneumonitis treated?
    remove antigenic exposure (most important!!!)
    immunosuppression if:
    • symptomatic
    • extensive (lots of lung affected)
    • progressive (loss of lung function)
  • What is Sarcoidosis?
    abundance of tightly packed (well circumscribed) granulomas in a lymphatic distribution
    Can affect almost any part of the body, but the lungs and thoracic lymph nodes are the most common
    unknown trigger
    symptoms: systemic (fever, weight loss, night sweats, fatigue, depression) likely due to elevated levels of cytokines in blood
    mainly affects adults ages 20-60 with black ppl having higher risk
  • How does Sarcoidosis present upon examination?
    thickening along small airways from granuloma formation in airway lymphatics
    upper lung zones more affected than lower
  • How is Sarcoidosis treated?
    immunosuppression meds (eg corticosteroids) if progressive (as have lots of side effects)
    monitored w/o treatment if stable
  • What is CTD-ILD?
    Connective Tissue Disease-Interstitial Lung Disease
    • nearly any ILD pattern can happen in CTD (most common NSIP & organising pneumonia)
    • inflammatory CTD-ILD can convert, over time, to fibrosis (in UIP pattern)
    eg scleroderma, rheumatoid arthritis, dermatomyositis / polymyositis, Sjorgen's,
  • How is CTD-ILD treated?
    immunosuppression if symptomatic, extensive, progressive
    treatment not always effective
  • What is drug-related ILD?
    causes: chemotherapy meds, amiodarone, long-term use of nitrofurantoin
    imaging findings: ranging from mild inflammation to severe fibrosis
    diagnosis often made without biopsy (due to non-specific nature of inflammation)
  • How is drug-related ILD treated?
    stop medication (MOST IMPORTANT)
    difficult decisions regarding stopping treatment but must be done
    treat with immunosuppression if symptomatic, extensive or progressive
  • What is occupational lung disease?
    Work-related lung conditions.
    • asbestos-related disease
    • lung cancer
    • mesothelioma
  • What is pneumoconiosis?
    Lung disease caused by inhaling dust particles.
    nodular disease is a common finding in silica & coal dust exposure, causing 'progressive massive fibrosis'
    asbestos fibres often get stuck in lymphatics near pleural, causing 'pleural plaques'
  • What is 'asbestosis'?

    disease due to fibrotic response to asbestos fibres
    causes reticulations and honeycomb cysts on imaging
  • What can asbestos cause?
    1. Asbestosis
    2. Mesothelioma (pleura cancer)
    3. Lung cancer
    can cause pleural plaques
    which increase risk
    highest risk of lung cancer = smoking + asbestos exposure
  • What is 'coal miner's lung'?
    very small coal dust particles reach airsacs
    • engulfed by macrophagesinflammation
    • trigger massive fibrosis
    essentially lasts forever in lung
  • What is the latency period for asbestos-related disease and coal-miner's lung?
    years after exposure
    asbestos-related: can be decades
    coal-miner's: within years
  • Do all fibrotic ILDs start with inflammation?
    no
    IPF does not have typical inflammatory pro-dome phase
  • What is Idiopathic Pulmonary Fibrosis (IPF)?
    reticulations + honeycomb cysts
    mostly affects lower + peripheral aspects of lung
    UIP pattern
    common, old age (rare before 50)
    most patients have smoked, but disease process not understood so 'idiopathic'