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8/3/2019 Hypersensitivity Pneumonitis Final
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Dr. Muhammad Amin
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Alternative Names
Extrinsic allergic alveolitis; Farmer's lung; Mushroom
picker's disease; Humidifier or air-conditioner lung; Bird
breeder's or bird fancier's lung
Hypersensitivity pneumonitis usually occurs in people who
work in places where there are high levels of organic dusts,
fungus, or molds.
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Bird fancier's lung is the most common type of HP. It is
caused by repeated or intense exposure to proteins found in
the feathers or droppings of many species of birds.
Farmer's lung is caused by exposure to dust from moldy
hay, straw, and grain.
These exposures can lead to lung inflammation and
acute lung disease. Over time, this acute condition may turn
into long-lasting (chronic) lung disease. HP is thought to be more common in non Smoker
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The term HP, is immunologically mediated, predominantly
interstitial lung diseases caused by inhalation of organic
dust related to occupational and environmental exposureantigen to which the individual has been previously
sensitized, primarily involves alveoli.
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These disorders account for about 15% of non infectious
diseases seen by pulmonary physician
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Bird fancier's lung
Also called bird breeder's lung,
pigeon breeder's lung, and poultry
worker's Lung.
Avian proteins Feathers and bird droppings[8]
Farmer's lung
The molds
Thermophilicactinomycetes[8]
Aspergillus species
Saccharopolyspora rectivirgula
,
and
Micropolyspora faeni
Moldy hay
Bagassosis Thermophilic actinomycetes[8]
Moldy bagasse (pressed
sugarcane)
Bird fancier's lung
Also called bird breeder's lung,
pigeon breeder's lung, and poultry
worker's Lung.
Avian proteins Feathers and bird droppings[8]
Farmer's lung
The molds
Thermophilicactinomycetes[8]
Aspergillus species
Saccharopolyspora rectivirgula
,
and
Micropolyspora faeni
Moldy hay
Bagassosis Thermophilic actinomycetes[8]
Moldy bagasse (pressed
sugarcane)
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Acute:
Influenza like symptoms begins 2-9 hours after exposure
Short period of exposure to high dose of antigen and
reversible. Peak typically 6-24hrs
Cough and dyspnea are common but not universal
Spontaneous resolve in 2-5 days
Recurrent symptoms when exposed to causative agents
Physical Examination => crackle
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Sub acute:
Gradual onset over several days to weeks
Marked dyspnea and cough may progress to severe
dyspnea and cyanosis leading to urgent hospitalization Mild symptoms
Extend over 10- 14 days
Usually reversible
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Chronic
Insidious onset over a period of month with increasing
cough and exertional dyspnea
Fatigue and weight loss may be prominent symptoms No fever
Chronic exposure to low antigen dose and is less reversal
able
Absence of clubbing of finger
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Immune complex mediated reaction
Cell mediated reaction=> granuloma formation
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Most patients have circulating immunoglobulin G antibodies
that are specific for the offending antigen. The antibody
(called precipitating antibody) reacts with a specific antigen
to form a precipitation.
Early response to the antigen is characterized by an
increase in neutrophils in the alveoli and small airways
followed by an influx of mononuclear cells. These cells
release proteolytic enzymes, prostaglandins, and
leukotrienes, play important roles in hypersensitivity
pneumonitis pathogenesis.
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Symptoms ofacute hypersensitivity pneumonitis may occur 4 -6 hours after you have left the area where the foreign substance isfound, making it difficult to find a connection between youractivity and the disease. Symptoms may include:
Chills
Cough
Fever Malaise
Shortness of breath
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Symptoms ofChronic Hypersensitivity Pneumonitis may
include:
Breathlessness, especially with activity
Cough, often dry
Loss of appetite
Unintentional weight loss
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Blood tests
Tests of molds from your workplace
Chest x-ray
HRCT scan of the chest
Lung function tests
Challenge test, in which you inhale the materials to which you are
sensitive to test your reaction
Lung biopsy
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Posteroanterior (PA) chest radiograph in a patient with chronic hypersensitivity
pneumonitis (HP)a pigeon fanciershows reticular-nodular opacification..
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Light microscopy shows mononuclear infiltration and noncaseating
granulomas. This finding is usually seen in acute disease, but it can also
appear in sub acute and chronic disease
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1. symptoms compatible with HP
2. evidence of exposure to appropriate antigen by history or
detection in serum and/or BAL fluid antibody
3. findings compatible with HP on chest radiograph or HRCT
4. BAL fluid lymphocytosis
5. pulmonary histologic changes compatible with HP
6. positive natural challenge
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1. Bibasilar rales
2. Decreased DLCO
3. Arterial hypoxemia, either at rest or during
exercise
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Asbestosis
A typical Pneumonias
Sarcoidosis Metastatic Cancer, Unknown Primary Site
Miliary Tuberculosis
Pneumonia, Viral
Drug induced Lung disease
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Contact avoidance exposure(job changing)
Environmental control
Changes in Industrial procedure Improve Ventilation
Air Mask ,Air Filtrating system
Drying of Hay prior to storage
Spraying of Bagasse with dilute propionic
acid
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Antipyretic & supplementary oxygen
Oral corticosteroids
20-50mg/day or 0.5 mg/kg/d for 2-4 weeks in
acute and maybe longer in sub acute and
chronic HP
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Highly variable
Is excellent following removal from antigen
exposure in Acute HP Recurrent episodes of acute HP do not
necessarily progress to chronic HP
Chronic HP may eventually lead to corPulmonale and death
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THANK YOU
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1. All of the following agents have been shown to cause both
occupational asthma and hypersensitivity pneumonitis EXCEPT:
A. Toluene diisocyanate
B. Trimellitic anhydride
C. Micropolyspora faeni
D. Bacillus subtilis
E. Diphenylmethane diisocyanate
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Which of the following groups of symptoms are common in
the chronic form of Hypersensitivity Pneumonitis?
A. Progressive dyspnea, cough, fever
B. Malaise, weakness, fever
C. Cough, malaise, anorexia
D. Cough, weakness, myalgias
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The immunologic basis of hypersensitivity pneumonitis
appears to be:
A. Type 3 (immune complex)
B. Type 1 (IgE)
C. Type 4 (Cell mediated)
D. Combination of Type 3 and Type 4
E. Combination of Type 1 and Type 3
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Which antigens are capable of inducing Hypersensitivity
Pneumonitis?
A. Bacteria, rodent products, plant products, and prions
B. Bacteria, viruses, low molecular weight chemicals,
and certain drugs
C. Fungi, amoebae, avian products, and certain drugs
D. Prions, viruses, bacteria, and fungi