L67 – Diffuse Interstitial Lung Diseases Flashcards Preview

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Flashcards in L67 – Diffuse Interstitial Lung Diseases Deck (65):
1

Describe Diffuse Intersitital Lung Disease?

group of heterogeneous diseases

caused by a number of etiology (known or unknown)

causes Diffuse damage to pulmonary interstitium

2

What are the 3 components of pulmonary interstitium?

PAP

tissues of gas-exchange unit

 Peribronchiolar tissue
 Alveolar septa
 Perivascular tissue

3

Name the MILD Acute interstitial lung disease and give an example of its cause?

Interstitial pneumonitis

e.g. caused by mild viral infectiuon

4

In acute interstitial lung disease, describe the interstitial tissue?

Interstitial tissue infiltrated by lymphocytes, macrophages, plasma cells

5

Name the SEVERE Acute ILD ?

diffuse alveolar damage (DAD)

6

Name some COMMON causes of LUNG injuries in DAD (Severe Acute ILD)?

Common:
- Gastric aspiration (vomit, acid enters lungs)

- Infections from inhaling infectious agents (e.g. Virus, bacteria)

7

Name some UNCOMMON causes of LUNG injuries in DAD?

Toxic fume inhalation,

drowning,

post-lung transplant immune reaction

8

Name some COMMON causes of GENERAL injuries in DAD (Severe Acute ILD)?

Sepsis
Shock
Severe trauma (caused by hypoxic blood, low BP)

9

Name some UNCOMMON causes of GENERAL injuries in DAD (Severe Acute ILD)?

Acute pancreatitis
Drug overdose

10

What is the pathogenesis of DAD?

Severe injury to epithelium and/or endothelium

> Release inflammatory cytokines for WBC

> Causes necrosis of alveolar wall (damage endothelium and pneumocytes)

11

What are the consequences of necrosis of alveolar wall in DAD?

Alveolar wall necrosis:

1. Damage endothelium, interstitial cells >>> capillary leak

2. Lose alveolar pneumocytes >>> lose alveolar surfactant

12

What are the physiological effects of DAD?

Lose alveolar surfactant >> decrease lung compliance due to increase surface tension >> alveolar airspace collapse

>> not ventilated but perfused

>> ventilation/perfusion (VQ) mismatch

13

What replaces the necrotic alveolar wall? What is the result?

Type II pneumocytes try to regenerate and
differentiate into type I

>> result in cuboidal, hyperplasia of type II pneumocytes

14

Explain the formation of Hyaline membrane in DAD?

Alveolar wall necrosis > damaged endohelium and pneumocytes

>> Escaped RBC, serum protein + fibrinous exudate, cell debris accumulation

INSPIRATION pushes exudates to outer airspace

>> Hyaline membrane form

15

What is the effect of hyaline membrane?

Lower diffusion capacity

16

Summarize all the structural changes to alveolar wall in DAD?

Congested and dilated capillaries

Form Hyaline membrane

Type II pneumocyte hyperplasia

Interstitial edema + mononuclear exudate

17

What is the effect of V/Q mismatch in DAD?

Severely impaired gas exchange

18

What is the clinical term for Severe acute Interstitial lung disease/ DAD?

Acute Respiratory Distress Syndrome (ARDS)

19

What is the mortality of acute respiratory distress syndrome (ARDS)?

30-40% (surviving patients may develop lung fibrosis due to repair)

20

DAD, interstitial pneumonitis belong to Acute ILD. Descibe Chronic ILD?

Group of heterogenous diseases that causes diffuse injury to lung interstitium

** caused by chronic inflammation and lung fibrosis

21

What causes Chronic ILD? *think what type of injury*

Recurrent/ continuous/ severe lung damage

Initial injury may be asymptomatic

22

Could a viral infection lead to Chronic ILD?

If the infection is mild/ transient, then no

23

What are the 4 major causes of Chronic ILD?

TAMO

Toxic damages

Autoimmune diseases

Mineral dust deposition

Others (allergy, sarcoidosis...etc)

24

List some Toxic damages that can lead to Chronic ILD?

 Toxic fume
 Irradiation (e.g. radiotherapy)
 Cytotoxic drugs
 Prolonged treatment with hyperbaric O2

25

What is the name of the condition caused by mineral dust deposition in lungs?

pneumoconiosis

26

What autoimmune diseases can lead to chronic ILD?

Systemic sclerosis (aka scleroderma)

Systemic lupus erythematosus (SLE)

27

What type of hypersensitivity reaction is Sarcoidosis?

type IV: delayed-type hypersensitivity (DTH)

28

What type of allergic condition can lead to chronic ILD?

extrinsic allergic alveolitis

29

Give 2 examples of Chronic ILD

1) Idiopathic pulmonary fibrosis**
2) Pneumoconiosis


(** No longer called cryptogenic fibrosing alveolitis**)

30

What is the progression of Idiopathic pulmonary fibrosis (chronic ILD) dependent on?

Disease progression = slow, insidious

depends on individuals, severity of injury

31

What gender is more affected by Idiopathic pulmonary fibrosis ?

Female

32

What is the signature histological feature of advanced stage Idiopathic pulmonary fibrosis ?

Honeycomb lung

33

What is the initial injury for Idiopathic pulmonary fibrosis ? What type of injury is caused?

Unknown agent, hence idiopathic

persistent, chronic, diffuse lung injury on tissue**

**not in airspace or airway

34

What is the pathology of Idiopathic pulmonary fibrosis?

Unknown agent cause persistent, chronic, diffuse lung tissue injury/ damage

>> B and T lymphocyte activation > Production of cytokines and Antibodies

>> Activate macrophage
>> recruit neutrophils, induce fibroblast proliferaton + release oxidants and proteases

>> Damage to type I pneumocytes

35

What is the pathological result of idiopathic pulmonary fibrosis at distal airways?

Fibroblast proliferation causes fibrosis**
+
Bronchiolar epithelium grows in / extends to line airspaces

Overall: distal airway is “amputated", reduce SA

36

Explain the end stage manifestation of idiopathic pulmonary fibrosis?

Distal airways become "amputated"

>> Acini "simplified" to become cystic spaces

>> Bronchiolar epithelium grows into cystic spaces

>> Honeycomb lung

37

Summarize the pathological features of Idiopathic pulmonary fibrosis?

Interstitial fibrosis >> "amputated" distal airways and honeycomb lungs

Obliteration or Cystic dilatation of air spaces

May associate with chronic inflammatory cells

38

Summarize the macroscopic appearance of Restrictive pattern lung damage in Acute ILD?

Thickened alveolar wall
Rigid, shrunken lungs
Pin-like airspaces

>>Type I respiratory failure

39

Summarize the macroscopic appearance of End-stage lung damage in Chronic ILD?

Dense interstitial fibrosis

Amputated airways and honeycomb lungs

Oliterated or cystic air spaces

40

What are the affected lung functions due to interstitial fibrosis?

Decrease compliance / increase elastic recoil

41

What are the gross results of interstitial fibrosis?

Stiff, rigid lungs

Restictive lung function

42

What are the affected lung functions due to congested/ damaged alveolar capillaries?

Imparied perfusion, ths gas exchange

43

What are the affected lung functions due to Alveolar wall fibrosis?

Increase wall thickness and decreased surface area

>> Decrease diffusion capacity and gas exchange

>> Lower ventilation = V/Q mismatch

44

What are some clinical examination features of end-stage diffuse ILD?

Dry cough
Shortness of Breathe without wheezing
Cyanosis *due to V/Q mismatch)

45

What is observed in CXR for end-stage diffuse ILD?

Corase lines and cystic nodules observed

46

End-stage diffuse ILD increases the risk of ___?

Lung cancer

47

How does chronic hypoxia caused by end-stage diffuse ILD manifest? (think early and late progressions)

Chronic hypoxia > Pulmonary vasoconstriction > Obliterate vessel lumen

Early = reversible vasoconstriction

Late = irreversible structural changes

48

What are some irreversible structural changes in End-stage diffuse ILD?

Increase in fibroblast proliferation and SM cells

Thickening of tunica intima and media

49

How to diagnose ILD?

*clin- radi- patho*

Based on a combination of features:
Clinical,Radiological,Pathological

+

Identify etiology from history, relevant tests

50

What drug has no effects on honeycomb lungs?

NSAIDs

51

Why is tissue examination important in diagnosing ILD?

 Assess disease activity (active inflammation vs. fibrosis)

 Find the cause (e.g. exposure to asbestos bodies > asbestosis)

52

Describe Pneumoconiosis?

lung fibrosis resulting from inhalation of inorganic dusts

53

What are some determinants of chronic inflammation in pneumoconiosis?

Chemical nature, physical state, particle size of dust

Duration, concentration of exposure

54

What is the agent and exposure period causing Silicosis?

exposure to silica = silicon dioxide (SiO2)

Prolonged, chronic exposure (>10-20 years)
or
Massive exposure

55

What are some high risk occupations for silicosis?

quartz-mining, rock-cutting, glassmaking, pottery, sand-blasting

56

Describe the pathogenesis of silicosis.

Silica deposit in alveolar wall > macrophage release FIBROGENIC FACTORS

> Fibroblast proliferation and collagen deposition

> SILICOTIC NODULES FORM

57

Compare the extent of silicotic nodules in simple and advanced silicosis?

Simple: sporadic, white nodules spread throughout lung

Advanced: Massive areas of fibrosis with concentrically deposited collagen

58

Advanced silicosis can lead to what conditions?

Cor pulmonale
Respiratory failure
Honeycomb lung

59

What is the agent and duration of exposure of Asbestos?

Fibrous magnesium silicate
(Long/thin, curved or straight)

prolonged / heavy exposure

60

Sources of asbestos?

acoustic / thermal insulator,
industries, old buildings

61

What is the hallmark of Asbestosis?

Asbestos bodies

asbestos fibers covered by a film of protein impregnated
with haemosiderin*** (RBC breakdown products)

62

Appearance and location of asbestos bodies?

Long, beaded, brown

In bronchial fluids, sputum

63

Describe the pathology of asbestosis?

asbestos deposit in airspace

Macrophage fails to ingest asbestos, fibroblast proliferation > Interstitial fibrosis

Puncture of endothelium, bleeding >> RBC broken down by asbestos and deposits haemosiderin >> Asbestos bodies

64

What are some asbestos related conditions?

Lung cancer > Malignant mesothelioma

cancer derived from lining (mesothelium) of pleura, pericardium, peritonium

65

Chronic hypoxia increases risk of developing which diseases?

Cor pulmonale (RHF)
Pulmonary Hypertension
Polycythaemia

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