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Extrinsic allergic alveolitis Hypersensitvity pneumonitis ปอดอักเสบภูมิไวเกิน

Extrinsic allergic alveolitis Hypersensitvity pneumonitis ปอดอักเสบภูมิไวเกิน. ศ . น . พ . อรรถ นานา คณะแพทยศาสตร์ศิริราชพยาบาล มหาวิทยาลัยมหิดล. HP: Introduction. immunologically induced lung disease diffuse inflammation of lung parenchyma & airways in previously sensitized patients

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Extrinsic allergic alveolitis Hypersensitvity pneumonitis ปอดอักเสบภูมิไวเกิน

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  1. Extrinsic allergic alveolitisHypersensitvity pneumonitisปอดอักเสบภูมิไวเกิน ศ.น.พ. อรรถ นานา คณะแพทยศาสตร์ศิริราชพยาบาล มหาวิทยาลัยมหิดล

  2. HP: Introduction • immunologically induced lung disease • diffuse inflammation of lung parenchyma & airways in previously sensitized patients • sensitized to repeated inhalation of dusts containing organic & low molecular weight chemical antigens

  3. HP: Introduction • dusts derived from • dairy & grain products • animal dander & proteins • wood bark • water reservoir vaporizers • not atopic disease • not associated with increase IgE or eosinophils

  4. HP: Selected etiological agents Disease Farmer’s lung ปอดชาวไร่ Bagassosis โรคชานอ้อย Bird-breeder’s lung Bird-fancier’s lung Pigeon-breeder’s lung Mushroom-worker’s lung คนเพาะเห็ด Humidifier/air conditioner lung ปอดเครื่องทำความชื้น ปอดอักเสบการระบาย อากาศ Source หญ้าแห้งที่ขึ้นรา ชานอ้อยที่ขึ้นรา มูลนก, ขน (พิราบ,นกแก้ว) ปุ๋ยที่ขึ้นรา,หญ้าแห้ง เครื่องทำความชื้น ท่อเครื่องปรับอากาศ Antigen Micropolyspora faeni Thermoactinomyces sacchari Avian proteins Thermoactinomyces vulgaris Micropolyspora faeni Thermoactinomyces vulgaris

  5. HP: Epidemiology • Varies • 0.5-5% of farmers (Farmer’s lung disease) • 8-30% of members of pigeon breeding clubs (pigeon breeder’s disease) • Prevalence Farmer’s lung UK France Finland U.S.A. 420-3000 4370 1400-1700 540 cases/100,000 / “ “ “ persons at “ “ “ risk “ “ “

  6. Bagassosis : A Report of 8 Cases จดหมายเหตุทางแพทย์ 2517:57;468-74. Pee Kamtorn, M.D.* Poonkasem Charoenpan, M.D.** Yosvi Sukumalchantra, M.D. , F.A.C.P. , F.R.C.P. (C) ,F.A.C.C.** Vijitr Boonpucknavig, M.D.*** Kalyanakit Kitiyakara, M.B. , B.S. , M.R.C.S. , L.R.C.P.**** Chirotchana Suchato, M.D.***** Chaivej Nuchprayoon, M.D.****** Bagassosis is classified as an extrinsic allergic pneumonia. It is considered to be the result of allergic reaction to moldy sugar cane inhalation(1) . Case Report All of the patients worked at a paper produc- tion factory in Karnchanaburi province and were

  7. HP : Pathogenesis • immune - complex mediated process • precipitating Ab against specific Ag • 50% of asymptomatic persons exposed also have Ab

  8. HP: Pathogenesis • cell - mediated immunity more important • response • increase PMN in alveoli & small airways • influx of mononuclear cells • formation of granulomas • cytokine from T- lymphocytes & macrophages

  9. HP : Histologic findings • diffuse interstitial infiltrate : lymphocytes, macrophages, mast cells, plasma cells • scattered noncaseating granulomas • cellular inflammation of bronchioles, + bronchiolar obstruction • absent generalized vasculitis, necrotizing granulomata ~ duration or stage of disease, adequacy of biopsy sample

  10. HP : Diagnostic criteria Major criteria 1. Symptoms c/w HP , appear or worsens within hours after Ag exposure 2. Confirmation of exposure to the offending agent by - Hx -investigation of the environment -serum precipitin test -BAL Ab

  11. HP : Diagnostic criteria 3. Compatible CXR or HRCT 4. Lymphocytosis in BAL 5. Compatible histologic changes 6. Positive “natural challenge” or by controlled inhalational challenge

  12. HP : Diagnostic criteria Minor criteria 1. Basilar crackles 2. Decreased diffusion capacity 3. Arterial hypoxemia, at rest or with exercise

  13. HP : Diagnostic criteria Four major criteria Two minor criteria Other diseases have been excluded Adapted from Schuyler + Cormier Chest 1997; 111: 534-6.

  14. HP : Diagnosis • often unrecognized & misdiagnosed • respiratory symptoms with Hx. of • environmental • occupational exposure • respiratory symptoms with episodic radiographic infiltrates “Recurrent pneumonia”

  15. HP : Radiographic findings • vary to the stage of disease • acute HP • bilateral micronodular (1-4 mm.) infiltrates • patchy ground-glass opacities • decreased attenuation (air trapping from bronchiolitis) and mosaic pattern (expiratory view)

  16. HP : Radiographic findings • Subacute HP • fine linear shadows, small nodules = reticulonodular appearance • Chronic HP • volume loss • reticulonodular infiltrates • honeycombing • predominantly upper & mid lung zones

  17. HP : Pulmonary function tests • restrictive changes • (superimposed obstruction in chronic HP) • decreased diffusing capacity • ABG: increased alveolar-arterial oxygen gradient • frank hypoxemia (severe cases) • oxygen desat. with exercise (clue in suspected case)

  18. HP : BAL fluid • intense lymphocytosis • predominantly CD 8+ T-suppressor cells ~ timing of the last antigen exposure, stage of disease

  19. HP: key features Immunopathology alveolitis, immune complex granulomas, bronchiolitis lymphocytic infiltration, fibrosis,air space destruction Prognosis good good good Acute Subacute Chronic Time frame 4-48 hr weeks to 4 M. 4 M. to years Clinical features fever, chills, cough hypoxemia, aches dyspnea , cough, episodic flares dyspnea, cough, fatigue, weight loss HRCT ground glass infiltrates micronodules, air trapping fibrosis, honey combing, emphysema

  20. HP : Differential diagnosis • Acute stage • pneumonia • acute tracheobronchitis • organic dust toxic syndrome • BOOP

  21. HP : Differential diagnosis • Subacute stage • recurrent pneumonia • granulomatous lung diseases • pneumoconiosis • Wegener’s granulomatosis

  22. HP : Differential diagnosis • Chronic stage • IPF • bronchiectasis • COPD with pulmonary fibrosis • MAC

  23. HP: Management • early diagnosis • avoidance of further exposure • protective devices :- personal respirators • relocation to a new job • reducing microorganism contamination in the environment • altering handling & storage • wetting compost • using antibiotics to decrease fungal growth • preventive maintenance on all A/C equipment

  24. HP: key features Immunopathology alveolitis, immune complex granulomas, bronchiolitis lymphocytic infiltration, fibrosis,air space destruction Prognosis good good good Acute Subacute Chronic Time frame 4-48 hr weeks to 4 M. 4 M. to years Clinical features fever, chills, cough hypoxemia, aches dyspnea , cough, episodic flares dyspnea, cough, fatigue, weight loss HRCT ground glass infiltrates micronodules, air trapping fibrosis, honey combing, emphysema

  25. Subacute HP, a 60-year-old dairy farmer had a 8-year history of intermittent dyspnea. CXR shows bilateral reticulonodular interstitial infiltration.

  26. Chronic HP, Pigeon breeder’s disease. Bilateral reticulonodular densities are present.

  27. Acute HP, ground glass opacification

  28. HRCT of a patient with Chronic HP demonstrating centrilobular nodules not associated with bronchovascular bundles.

  29. Chronic HP, honeycombing in right upper lung & traction bronchiectasis

  30. Acute HP, mononuclear infiltration & noncaseating granulomas.

  31. Chronic HP, mostly lymphocytic cellular infiltrate with epithelioid cells & numerous and clearly defined granuloma. (Wright-Giemsa)

  32. Giant cells are characteristic feature of HP.

  33. Chronic HP shows interstitial inflammation associated with fibrosis.

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