HP By ziba Loukzadeh MD Occupational Medicine department Yazd University of Medical Sciences Definition Immune hypersensitive response Extrinsic allergic alveolitis granulomatous interstitial bronchiolar and alveolarfilling lung diseases caused by ID: 310826
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Slide1
Hypersensitivity Pneumonitis(HP)
By :
ziba
Loukzadeh
, M.D
Occupational Medicine department
Yazd University of Medical SciencesSlide2
DefinitionImmune (hypersensitive) response
Extrinsic allergic alveolitis: granulomatous, interstitial, bronchiolar and alveolar-filling lung diseases caused by
repeated
exposure and subsequent sensitization to a variety of organic and chemical antigensSlide3
EtiologyMicrobial agents
Animal proteins
Low molecular weight chemicalsSlide4
Microbial agents
Bacteria
-Farmer’s lung -Bagassosis -Mushroom worker’s lung
Fungi
-Wood pulp worker’s lung
-Cheese washer lung
Ameba
-Humidifier lung
Slide5
Bacteria
cause
occupation
Agent
source
Major
antigen
Farmer's lung
Agriculture worker
Moldy hay
thermoactinomycet
Mushroom worker's
Mushroom worker
Compost
thermoactinomycet
Bagassosis
Bagass worker
Moldy
sugarcane
thermoactinomycetSlide6
Animal proteinsAvian proteins : Bird breeder’s lung
Urine ,Serum ,Pelts : Animal handler’s lung
Wheat weevil : Wheat weevil lung Slide7
ChemicalsIsocyanate HP
TDI , MDI , HDI
TMA HP
Trimellitic anhydrideSlide8
PathogenesisImmunology
Repeated inhalation of antigens
sensitization immunology response(type III,IV) influx of neutrophiles shift T lymphocytes (~70%)(predominantly of CD8)
Antibodies in HP are IgG classResponse delay by 3-8 hoursSlide9
Pathogenesis (cont’)Host factors
-Non smokers > smokers
-Polymorphism in TNF-α gene -No association with HLASlide10
Pathogenesis (cont’)
Exposure factors:
-Ag concentration
-Duration of exp. -Frequency & intermittency of exp. -Particle size -Use of respiratory protection
Farmer's lung disease: winter
Bird breeder's lung: summer
Indirect exposureSlide11
Clinical features
Acute HP : fever ,chill ,myalgia ,cough & dyspnea + basilar
rales
in Ph/E (4-12 h after heavy exp. ) Recurrent febrile episodes (most frequent presentation)Subacute & chronic HP : insidious onset of respiratory symptoms ,malaise , fatigue , weight loss + basilar rales ,wheezing cyanosis ,right sided HF in Ph/E Slide12
DDxInhalation fevers
others granulomatous disorder(Sarcoidosis)
immunologic disease (Asthma)
infection fibrotic lung disease (IPF)Slide13
Comparison HP& Inhalation fever
Feature
HP
Inhalation fever
Example
Farmer`s lung disease
Metal fume fever
Etiology
Thermoactinomyces
Zinc fume fever
pathophysiology
Hypersensitive reaction
Cytokine- mediated (??)
Exposure dose
Low dose
High dose
Sensitization required
Yes
NoSlide14
Comparison HP& Inhalation fever(cont´)
Feature
HP
Inhalation fever
Fever
Yes
Yes
Flu-like syndrome
Yes
Yes
Cough
Expected
Not necessary
Dyspnea
Yes
Not typically
Chest exam
Rales
normalSlide15
Comparison HP& Inhalation fever(cont´)
Feature
HP
Inhalation fever
CXR
Alveolar infiltration
No
PFT
Decreased DLCO&volums
Minimal change
BAL
Lymocytosis
Inincreased Neutrophiles
Chronic sequle
~yes
None
Natural Hx
Reccurent or progressive
Complete recovery within 3 daySlide16
Lab. studiesPrecipitin Ab:
Helpful but not specific, not sensitive, not hallmark
Leukocytosis ,mild elevation of ESR ,CRP , IgG , IgA ,IgM ,ACE ,ANASlide17
PFT Normal (early dis.)
Restrictive
Obstructive
Mixed decreased DLCO (most sensitive physiologic test in early HP )Slide18
CXR
Acute : diffuse ground glass ,fine nodular or
reticulonodular
pattern (lower lung )Subacute : reticulonodular patternChronic : fibrosis ,reticular opacity, honey combing mediastinal lymphadenopathy (up to 50%)Slide19
HRCT
Ground glass
Centrilobular nodules
Airspace consolidation Mosaic pattenFibrosis Emphysema Slide20Slide21
Normal CXRSlide22Slide23Slide24Slide25Slide26Slide27Slide28
HistopathologyClassic triad :
cellular bronchiolitis
lymphoplasmocytic interstitial infiltration
non-necrotizing granulomaSlide29
diagnosisTemporal relationship between symptoms and certain activities is often the first clue to the diagnosis of HPSlide30
diagnosisenvironmental history:
pets and other domestic animals
hobbies such as gardening and lawn care
recreational activities, for example, use of hot tubs and indoor swimming poolsuse of humidifiers, cool mist vaporizers, and humidified air conditioners moisture indicators such as leaking, flooding, or previous water damage to carpets and furnishingsSlide31
Diagnostic criteriaRequired
appropriate exposure
dyspnea on exertion inspiratory crackles lymphocytic alveolitisSupportive
recurrent febrile episodes
infiltrative on CXR
decreased DLCO
precipitating antibodies
granulomatous on lung biopsy
improvement with contact avoidanceSlide32
Treatment
Best treatment : Removal from exp.
Preferred approach : Elimination of Ag.
Oral corticosteroid : in severe or progressive diseaseO2 ,inhaled steroid & B-agonist in airflow limitationSlide33