Lec 15 ARDS Path

Question 1

Histologically what do you see with acute lung injury / ARDS?

Answer 1

mostly = see diffuse alveolar damage

less common = diffuse alveolar hemorrhage, acute eosinophilic pneumonia

Question 2

What is acute interstitial pneumonia?

Answer 2

idiopathic diffuse alveolar damage

Question 3

What are some common causes of ARDS?

Answer 3

• fulminant infection
• post trauma
• drug overdose
• sepsis
• aspirations

Question 4

What is pathogenesis of diffuse alveolar damage?

Answer 4

• not well understood

injury related to vascular endothelium and alveoli results in excess vascular fluid and protein leakage [early]

later –> cellular necrosis, epithelial hyperplasia, inflammation, fibrosis

Question 5

What is pathology of DAD?

Answer 5

• acute diffuse alveolar damage + necrosis of type I pneumoncytes
• exudation of protein rich fluid into alveolai that organizes into hyaline membranes

recovery = hyperplasia of type II pneumocytes and interstitial fibrosis

Question 6

What are the 3 overlapping phases of DAD?

Answer 6

• exudative phase [days 1-7]
• proliferative/organizing [7-12]
• fibrotic phase [> 21 days]

Question 7

What are gross features of lungs in ARDS?

Answer 7

• wet
• boggy
• airless
• heavy

Question 8

What do you see in exudative phase of DAD [1st wk after injury]?

Answer 8

• interstitial and alveolar edema
• fibrin exudate
• hyaline membranes [days 3-7]

Question 9

What is simple eosinophilic pneumonia? What usually causes it?

Answer 9

• mild self limited pulmonary infiltrates + peripheral blood eosinophilia

usually due to ascaris

Question 10

What do you see in tropical eosinophilic pneumonia? What usually cause it?

Answer 10

high fever, wheezing, peripheral blood eosinophilia

usually 2ndary to filarial infection

Question 11

What do you see in chronic eosinophilic pneumonia?

Answer 11

subacute illness; fever dyspnea peripheral blood eosinophilia

patchy infiltrates that resolve + reappear in same location

pt usually has asthma history

Question 12

Who get chronic eosinophilic pneumonia? What causes it?

Answer 12

• seen in patients with asthma history

can be idiopathic or due to drug toxicity, L-tryptophan ingestion, fungus, parasites

Question 13

What do you see in acute eosinophilic pneumonia?

Answer 13

• acute onset respiratory failure + severe hypoxemia

often have no peripheral blood eosinophilia; usually no history of asthma

Question 14

What do you see clinically/histologically in eosinophilic pneumonia?

Answer 14

• intra-alveolar fibrin, macrophages, abundant eosinophils, eosinophil microabscesses

+/- organizing pneumonia

Question 15

Eosinophilic pneumonia is sensitive to what treatment?

Answer 15

sensitive to steroids

Question 16

How do people with acute eosinophilic pneumonia represent?

Answer 16

may present with respiratory failure = clinically have ARDS

Question 17

What do you see histologically in acute eosinophilic pneumonia?

Answer 17

hyaline membranes like those in DAD but plus eosinophils

Question 18

What are histo features of classic/chronic EP?

Answer 18

intra-alveolar fibrin and macrophages

organizing pneumonia

Question 19

What is organizing pneumonia?

Answer 19

airspace organization = loos connective tissue in alveolar seen as common manifestation of lung injury as lung attempts repair

Question 20

What are some settings where you see organizing pneumonia?

Answer 20

• as primary porcess [OP pattern]
• as component of another process [HSP, acute pneumonia]
• secondary reaction adjacent to unrelated process [next to tumor, granuloma, abscess]

Question 21

What is organizing pneumonia pattern?

Answer 21

specific pattern of organizing pneumonia centered around small airways

presents in subacute way with SOB and cough

Question 22

What do you see histologically in OP pattern of organizing pneumonia?

Answer 22

• patchy bronchiolocentric organizing pneumonia
• may have fibroblastic plugs in small airway lumens
• minimal chronic inflammation in adjacent alveoli
• interveneing lung is normal
• no other significant findings

Question 23

What are potential etiologics of OP pattern?

Answer 23

• associated wtih collagen vascular disease, drug reaction

Question 24

What do you call idiopathic OP pattern?

Answer 24

cryptogenic organizing pneumonia [COP]