RHS10 - Pulmonary Pathology 5

Question 1

What is pneumoconiosis? What are the most common types of this diseaes?

Answer 1

Pneumoconiosis is a restrictive lung disease caused by inhalation of particulates or vapors. The most common kinds of pneumoconiosis are:

• Asbestosis
• Silicosis
• Coal Worker Pneumoconiosis (CWP)

Question 2

What determines the severity of symptoms of pneumoconiosis?

Answer 2

The fibrogenicity (potential to cause fibrosis) of the inhaled particle?

Question 3

List the particulates we need to know that cause pneumoconiosis and say how fibrogenic they are.

Answer 3

Fibrogenic - asbestos and silica

Inert or Weakly Fibrogenic - carbon and iron oxides

Question 4

Describe the general pathogenesis of pneumoconiosis diseases.

Answer 4

• Alveolar macrophages engulf the inhaled particle and release various lysosomal enzymes and free radicals, causing tissue injury which leads to inflammation and fibroblast proliferation.
• Alveolar macrophages also secrete growth factor IL-1, causing more fibroblast proliferation.
• The increased fibroblast proliferation leads to lung fibrosis

Question 5

What is the primary cause of asbestosis? What occupations are at greatest risk for this disease?

Answer 5

Asbestos (fibrous silicates)

Mining, milling, insulation, construction, and demolition

Question 6

Describe the specfific pathogenesis of asbestosis.

Answer 6

• Alveolar macrophages engulf asbestos fibers
• The macrophages cannot digest the fibers so they die, leaving behind an asbestos body which is an asbestos fiber surrounded by a protein and iron complex. The iron comes from the macrophage’s ferritin
• The body responds to the asbestos body by generating free radicals and secreting cytokines and other inflammatory mediators. This leads to cell injury and proliferation
• The increased cell injury and proliferation increases the rate of DNA damage and eventually leads to carcinogenesis

Question 7

Describe the histological appearance of asbestosis

Answer 7

Presence of asbestos bodies with appear as elongated, translucent particles with a beaded end

Question 8

List the various lesions associated with asbestosis.

Answer 8

• Lung
  
  • Asbestos bodies
  • Peribronchiolar fibrosis which can progress to diffuse interstitial fibrosis
  • Bronchogenic carcinoma
• Pleura
  
  • Plaques (collagen deposits)
  • Mesothelioma (malignancy of mesothelial cells in the pleura)

Question 9

Describe the gross features of asbestosis

Answer 9

Whitish, large, discrete, collagen plaques on the lung pleura (left)

Thick, firm, whitish pleural tumor (right)

Question 10

Important note about asbestos exposure, smoking, and lung cancer.

Answer 10

Asbestos and smoking are lung cancer risks independently but they drastically increase the risk for lung cancer if an individual is exposed to both.

Question 11

What is the cause of silicosis? What occupations are at the greatest risk for developing silicosis?

Answer 11

Inhilation of silicon dioxide (silica)

Mining, stonecutting, sandblasting, grinding, foundry work, and ceramic work

Question 12

Describe the gross appearance of silicosis.

Answer 12

A fibrotic and shrunken upper lobe

Question 13

Describe the histological appearance of silicosis.

Answer 13

Presence of central collagenous silicotic nodules with dust laden nodules on the periphery.

Question 14

What other diseases does silicosis increase the risk of? Why?

Answer 14

Pulmonary Tuberculosis

The silical inhibits the ability of the macrophages to kill phacgocytosed mycobacteria

Question 15

What is the cause of coal workers pneumoconiosis?

Answer 15

The inhalation of coal dust. But the carbon itself is actually harmless. The real problem is the organic and inorganic compounds also in the coal dust

Question 16

List and describe the categories of coal workers’ pneumoconiosis (CWP).

Answer 16

• Anthracosis
  
  • Accumulation of carbon pigment in the macrophages in the lymph nodes and perilymphatic regions. Asymptomatic
• Simple CWP
  
  • Carbon-laden (dust-laden) macrophages begin to aggregate into macules (smaller) and nodules (larger). Little to no fibrosis or pulmonary dysfunction
• Complicated CWP (progressive massive fibrosis)
  
  • Nodules coalesce and fibrous scars begin to appear (depending upon the amount of non-carbon material). There will be impaired pulmonary function

Question 17

Describe the gross appearance of CWP

Answer 17

The presence of antracotic pigment and fibrosis

Fibrosis can be spotted by looking at the pleural border. Fibrosis causes shrinking and if it present the border will be sunken in

Question 18

Give the definition of pulmonary edema and list the non-acrdiogenic causes we need to know.

Answer 18

The accumulation of fluid in the alveolar space

• ARDS (increased capillary permeability)
• High Altitude (exaggerated pulmonary capillary vasoconstriction in response to the hypoxic envrionment)
• Neurogenic (mechanism not completely understood)
• Pulmonary embolism (increased pressure)
  *

Question 19

What are the three things needed for thrombus formation?

Answer 19

• Hypercoagulability
• Stasis
• Endothelial Injury

Question 20

List the major risk factors for pulmonary thromboembolism

Answer 20

• Immobility (blood stasis)
• Surgery (both for immobility afterwards and because many surgeries (orthopedic) utilize prothrombotic measures)
• Severe Trauma
• CHF (stasis)
• Oral Contraceptive Pills (OCPs) (elevated estrogen increased coagulability)
• Disseminated Malignancy
• Hypercoagulability Disorders (Factor V Leiden, protein C, protein S, Anitthrombin III deficiency)

Question 21

What determines the Sx severity of a pulmonary thromboembolism

Answer 21

The percentage of pulmonary vasculature blocked (so one large or several smaller emboli) and cardiopulmonary status of the patient

Question 22

What are the consequences of a pulmonarythromboembolism?

Answer 22

• Upstream increase of PA pressure +/- vasospasm
• Ischemia (but usually not infarct) of downstream pulmonary parenchyma
• Acute increase in pressure on the right heart
• Secondary Hypoxia from
  
  • Atelectasis - reduced surfactant production in ischemic areas
  • Blood flow redirected to normally hypoventilated areas of the lung
  • R to L shunt through patent foramen ovale (30% of population)

Question 23

When can a pulmonary embolism lead to sudden death?

Answer 23

Sudden death from a pulmonary thromboembolism is usually the result of acute cor pulmonale (RH failure), shock, or hypoxia.

This usually only occurs if the embolus or emboli obstruct _>_60% of the pulmonary vasculature.

Question 24

What is a saddle embolus?

Answer 24

A large embolus lodged in the bifurcation of the pulmonary trunk

Question 25

Describe why the lung very rarely becomes infarcted and what usually causes it to become infarcted. Describe the gross appearance of a lung infarct.

Answer 25

The lung receives dual blood supply from the pulmonary and bronchial arteries. It only suffers ischemic necrosis (infarct) when there is pulmonary thromboembolism combined with a compromised CV status

A lung infarct typically occurs on the lung periphery and appears hemorrhagic and wedge shaped

Question 26

What is the primary symptom of most pulmonary thromboemboli?

Answer 26

Most are asymptomatic

Question 27

What is the definition of pulmonary HTN?

Answer 27

A mean PA pressure > 1/4 MAP

Question 28

List the types of pulmonary HTN and give examples for each type.

Answer 28

• Secondary (decreased cross-sectional area or increased blood flow)
  
  • COPD or Interstitial Lung Diseases (V-Q mismatch)
  • Recurrent pulmonary emboli
  • Heart disease (mitral stenosis, L to R shunt)
• Primary
  
  • Sporadic (idiopathic)
  • Familial - 50% of familial causes are from an autosomal dominant mutation to the BMPR2 gene (bone morphogenetic protein receptor), which codes for a receptor that binds to various TGFβ pathway ligands to inhibit smooth muscle proliferation.

Question 29

What are the clinical features of pulmonary HTN?

Answer 29

• Primary pulmonary HTN is most commonly seen in young women and secondary can be seen in any age/gender
• fatigue, syncope, dyspnea on exertion (DOE), and chest pain are typically seen
• cyanosis (if severe)
• If secondary, symptoms of underlying cause can also be seen.
• Right heart failure symptoms if untreated for 2-5 years

Question 30

List the histopathological findings seen in vessels experiencing pulmonary HTN.

Answer 30

• Pulmonary Trunk Vessels (large) - formation of atheromatous plaques
• Medium Sized Muscular Arteries - intimal cell and smooth and smooth muscle cell proliferation leading to wall thickening
• Small Arteries/Arterioles - thickening, medial hypertrophy, reduplication of the internal and external elastic lamina. Plexiform lesions - tufts of vasculature within the vessel wall

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