Pathology of Interstitial Lung Diseases

Question 1

pathologic patterns of interstitial lung disease

Answer 1

diffuse alveolar damage (DAD) - acute

organizing pneumonia (OP) - subacute

usual interstitial pneumonia (UIP) - chronic

non-specific interstitial pneumonia (NSIP) - chronic

granulomatous disease - acute, subacute, or chronic

Question 2

diffuse alveolar damage

Answer 2

acute lung injury resulting from infections, drug reactions, collagen vascular diseases, vasculitis, aspiration and inhalational injuries, ionizing radiation, pancreatitis, and uremia

early exudative phase and organizing phase

Question 3

pathogenesis of diffuse alveolar damage

Answer 3

damage to alveolar capillaries and epithelium

increased capillary permeability resulting in interstitial and intra-alveolar edema, fibrin exudation, and hyaline membrane formation

Question 4

DAD early exudative phase

Answer 4

necrosis of pneumocytes, endothelial cells

hyaline membranes in alveolar ducts

collapse of alveolar parenchyma

Question 5

organizing phase of DAD

Answer 5

organization of hyaline membranes

formation of airway space granulation tissue

dense collagenization of airway space granuation tissue

Question 6

specific pathologic findings that point to etiologies in DAD

Answer 6

Infectious organisms (bacteria, viral, fungal, pneumocystis: special stains)

Neutrophils (imply infection)

Eosinophils (Acute eosinophilic pneumonia)

Granulomas (infection, aspiration & drug reaction)

Aspirated food particles (aspiration)

Drug associated changes (foamy macrophages amiodarone; granulomas in methotrexate)

Diffuse hemorrhage & capillaritis (vasculitis)

Question 7

organizing pneumonia

Answer 7

sub-acute lung injury from any insult

infection

aspiration

drug reactions

minor component of many othe rdiseases cuh as hypersensitivity pneumonitis, NSIP, collagen vascular disease

Question 8

cryptogenic organizing pneumonia

Answer 8

idiopathic organizing pneumonia

consists of proliferation of granulation tissue within small airways

Question 9

usual interstitial pneumonia (UIP)

Answer 9

mostly idiopathic

caused by alveolitis, interstitial inflammation, patchy fibrosis with destruction of the underlying lung architecture

can be seen in collagen vascular diseases, drug reactions, familial/genetic disease, chronic hypersensitivity pneumonitis, and pneumoconiosis such as asbestosis

Question 10

morphology of UIP

Answer 10

thickening of the interstitial wall alternation with normal lung

cobblestoned pleura

patchy fibrosis and traction bronchiectasis

lower lobe and subpleural predominence in the fibrosis

honeycomb lung - end stage lung

Question 11

complications and causes of death in UIP

Answer 11

carcinoma of the lung

pulmonary hypertension/cor pulmonale

respiratory failure secondary to progressive fibrosis

pulmonary infections

acute exacerbations - acute lung injury superimpose don UIP (50% cause of death)

Question 12

non-specific interstitial pneumonia

Answer 12

chornic process of hypersensitivity pneumonitis, drug reactions, or collagen vascular diseases

no significant architectural distortion

diffuse mild ot moderate interstitial chornic inflammation with preservation of underlying lung architecture

cellular and fibrotic types

fibrotic has worse prognosis

Question 13

granulomatous disease

Answer 13

hypersensitivity pneumonitis

fungal and mycobacterial infections

aspiration

berylliosis

drugs

sarcoidosis - idiopathic disease

Question 14

hypersensitivity pneumonitis

Answer 14

extrinsic allergic alveolitis (EAA)

lung-limited hypersensitivity reaction to an inhaled antigen

known exposure to an offending agent

compatible clinical, radiologic, physiologic findings

BAL with lymphocytosis

Question 15

symptoms of acute HP

Answer 15

dyspnea, chills, fevers, shortness of breath 4 to 6 hours after exposure, resolves by 48 hours

Question 16

symptoms of sub acute HP

Answer 16

insiduous onset of SOB oer weeks to months, mild restrctive PFTs, marked lymphocytosis in BAL

Question 17

symptoms of chronic (fibrotic) HP

Answer 17

insiduous onset of SOP

restrictive PFTs

clubbing sometimes present

features of fibrotic interstitial lung disease on biopsy

old dense fibrosis always present

fibrotic NSIP, UIP like, centrilobular

interstitial, non-necrotizing granulomas, giant cells

Question 18

histologic features of HP

Answer 18

bilateral ground glass opacities and lobular areas of decreased attenuation and vascularity

interstitial inflammation with lymphocytes and plasma cells surrounding the bronchovascular bundles and extending into the surrounding interstitium

interstitial non-necrotizing granulomas or single giant cells, around bronchioles, in 2/3 cases

Question 19

histologic features of sarcoidosis

Answer 19

follow lymphatic route in hilar lymph nodes

prominent concentric lamellar fibrosis around granulomas

Question 20

nodular sarcoidosis

Answer 20

large nodules more than 1 cm in diameter

formed by aggregates of grnulomas

occasionally can show areas of necrosis

Question 21

berylliosis histology

Answer 21

indistinguishable from sarcoidosis

history of beryllium exposure

beryllium lym lymphocyte transformation testing

Question 22

aspiration pneumonia histology

Answer 22

organizing pnuemonia

aggregates of histiocytes surrounding food particle

not very well formed granulomas

food particle

presence of individual giant cells or foreign body granulomas

Question 23

Wegeners Granulomatosis

Answer 23

acute necrotizing granulomas of the upper and lower respiratory tract

acute necrotizing or granulomatous vasculitis of small to medium sized vessels

renal disease - glomerulonephritis

limited wegener’s in the absence of renal disease

pathogenesis is immune mediated

Question 24

pulmonary eosinophilia

Answer 24

tropical eosinophilia - caused by infection with microfilariae

chronic esoinophilic pneumonia - idiopathic, secondary to infection in association with asthma

Question 25

pulmonary alveolar proteinosis

Answer 25

unknown etiology - possible overproduction of surfactant by type 2 pneumocytes or its imparied clearance by alveolar macrophages

macrophage dysfunction

alveoli filled with dense, homogenous precipitate without any inflammation