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Flashcards in Hypersensitivity Pneumonitis -Goya Deck (18):
1

What is hypersensitivity pneumonitis?

inhaled dust or chemicals that produces an immunologically mediated inflammatory response of the alveoli and terminal bronchioles

2

What is acute hypersensitivity pneumonitis? What is an example?

-Most classic & easily recognized form of HP

-Symptoms characteristically occurs 4-6 hours after initial heavy exposure

-removal of exposure results in subsiding symptoms within 12 hours to several days

-Example: farmer’s lung

3

A 22-year old college student went for cave exploration during vacation. On the first day evening he went to nearby urgent care with acute SOB and mild fever. His vitals were stable and his chest x-ray shows diffuse bilateral infiltrate. He was given some bronchodilator and symptoms resolved by next day morning. Which of the following was most likely diagnosis?
A. Idiopathic pulmonary fibrosis
B. Sarcoidosis
C. Hypersensitivity pneumonitis
D. Tuberculosis

C. Hypersensitivity pneumonitis

4

what is the clinical presentation of subacute HP?

Characterized by gradual development of productive cough, dyspnea, fatigue, anorexia & weight loss

CXR maybe similar to acute HP

Similar findings may occur in patients who suffer repeated, infrequent acute attacks of HP

5

what is the clinical presentation of chronic HP?

May lack a history of acute episodes

Continuous or low intensity exposure for months to years (hot tub lung)

Insidious onset of cough, dyspnea, fatigue & weight loss

Fever or chills are usually absent

May progress to severe pulmonary fibrosis or cor pulmonale & may be difficult to differentiate from IPF

6

What are the PE findings in HP?

rales at the onset or shortly after acute exposure

rales persist for weeks after an acute attach or during the chronic stages

will not find rales when the pt is asymptomatic or when the CXR is normal

7

What are the lab findings in HP?

no single lab test

WBC range from 12,000-15,000 (eosinophilia is rare)

ESR will be elevated in acute HP but normal in subacute or chronic

8

What are the typical CXR findings in HP? Does a normal chest x-ray exclude an HP diagnosis?

no!

CXR has a low sensitivity in acute and subacute HP

symptoms are likely to be worse than the CXR

CXR in acute or subacute HP may show fine reticular pattern with multiple small defined nodules

Nodular shadows are usually diffuse, involving the middle & lower lung zones

With progression, the infiltrate will take a more coarse interstitial pattern or “honey-combing”

9

What will acute, subacute and chronic HP look like on high resolution CT?

Acute HP & subacute HP may show bilateral air-space consolidation, ground glass opacity & small ill-defined centrilobular nodules

Chronic HP often mirror those of IPF with honeycombing, irregular reticular opacities, traction bronchiectasis, ground glass opacity

10

What will the PFT findings be in HP?

acute attack=restrictive pattern

hypoxemia may be present

resp alkalosis is common

PFT abnormalities 4-6 hours after exposure and will show improvement 12-18 hours after removal of exposure

complete resolution in 1-6 months

11

What is a common histopathology finding in HP?

noncaseating granulomas

advanced stages have interstitial fibrosis

12

What is the diagnostic criteria for HP?

Characteristic signs & symptoms, radiographic findings and PFT data

Evidence of exposure to relevant antigen with plausible temporal relationship to clinical findings

Exclusion of other related illness

13

What is the treatment for HP?

antigen avoidance and corticosteroids

14

What are some helpful clues in recognizing HP?

History of recurrent atypical pneumonia, particularly if there is regularity to the illness (eg only in spring or fall, only certain time of week or following certain events)

Symptoms developed after moving to new job or home

Pets, especially birds, even if patient denies contact with pet (can include feather pillows, down blankets)

History of water damage to home or office, particularly to crawl space, basement, roof, ceiling tiles, carpet

Use of hot tub, sauna, swimming pool

Other people having similar symptoms or have left work because of recurrent symptoms

Patient feels better when away from home or work (vacation)

15

How does cigarette smoking affect the risk of HP?

higher frequency of HP in non-smokers than smokers

diminished antibody response to inhaled antigens due to the cigarette smoke

16

What causes Farmer's Lung?

inhalation of spores from Thermophilic Actinomycetes which proliferates in moldy hay

most common in winter and summer

common in areas with heavy rainfall and harsh winter conditions

17

Bird-Breeder's lung is commonly developed in people with exposure to what types of birds?

geese and ducks, turkeys, chicken and parakeets, doves

more continuous exposure --> more likely to see the chronic form of HP

caused by avian proteins from urine and feces

can also get from blankets/pillows

18

What is ventilation hypersensitivity pneumonitis?

antigenic exposure to organic material (thermophilic actinomycetes and aspergillus fumigatus) in contaminated ventilation systems

suspect if disease occurs in clusters or co-workers or multiple family members are affected

symptoms subside on weekends and vacations

exacerbations at end or shortly after the work day.

eliminated by disinfection, cleaning ventilation system