Extrinsic allergic alveolitis hypersensitivity pneumonitis, EAA

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Extrinsic allergic alveolitis(hypersensitivity
pneumonitis, EAA)

• Immunologically mediated inflammatory reaction in
  the alveoli and in the respiratory bronchioles
• causes organic dusts (lt5µm) moulds
  foreign proteins some
  chemicals diisocyanates
  organic acid anhydrides
• often heavy, repeated exposure, most often at the
  work place

hkes03
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EAA

• Pathology Granulomatotic inflammation around
  the alveoli and the peripheral bronchioles.Exudat
  e with plasma cells and lymphocytes.Macrophages,
  epitheloid cells and giant cells in the
  granulomas in the middle of the inflammation
  process.
• After the exposure ceases the reaction
  disappeares in 3-4 months.
• If the exposure continues, the exudation
  organises into fibrine and an irreversible
  pulmonary fibrosis follows.

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Examples of EAA Etiology

• Farmer's lung mouldy hay
• Saw mill worker's lung mouldy wood dust
• Bird fancier's lung proteins in bird
  droppings
• Mushroom workers lung spores, moulds
• Malt workers lung mouldy malt
• Humidifier lung contaminated
  humidifier water
• Cheese washer's lung Penicillium casei
• Suberosis cork dust mould
• Diisocyanate lung polyurethane hardeners
• Hard metal worker's lung hard metal dust, cobalt

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Allergic alveoltis in Finland 1981-2001(Finnnish
Register of Occupational Diseases)
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SRR (standardized risk ratio) of EAA in some
occupations
Occupation SRR n farmers and cattle
tenders 9.2 (8.4-10) 928 other printing workers
5.2 (2.2-13) 5 bookbindery workers 4.4
(1.7-5) 7 printers 4.1 (2.2-7.7) 10 wood
workers 2.9 (1.3-4.6) 13 typesetters 2.4
(1.3-4.6) 10 Keskinen et al. Työperäiset
hengtystieallergiat. Jauhoastmasta
sementti-ihottumaan.Työterveyslaitos, Helsinki
1997
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EAA, symptoms

• flu-like illness
• cough
• high fever, chills
• dyspnea, chest tightness
• malaise, myalgia4-8 hours after exposure
• chronic disease dyspnea in strain, sputum
  production, fatigue, anorexia, weight loss

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EAA, clinical findings

• Status dyspnea, cyanosis, crepitant
  rales digital glubbing (chronic form)
• Chest X-ray normal or small nodules/diffuse
  infiltrates/ ground glass appearance chronic
  form pulmonary fibrosisHRCT normal or ground
  glass appearance centrilobular micronodules
• lung function restriction, diffusing capacity
  decreases, hypoxemia, obstruction,
  hyperreactivity
• lab. tests rise of sedimentation
  rate, leukocytosis, neutrophilia
• BAL marked lymphocytosis, T helper / T
  supressor cells decreased

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EAA HRCT, acute disease
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EAA HRCT, chronic disease
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Diagnostics of EAA

• Main criteria1. Exposure to arganic dust
  (history, spesific IgG antibodies, work place
  measurements).2. Typical symptoms3. Chest X-ray
  findings
• Additional criteria1. Decreased diffusion
  capacity3. Hypoxia during rest or decreasing
  during excercise4. Restriction in spirometric
  values5. Lung biopsy with findings of allergic
  alveolitis6. Provocation test (at work place)
  positiveAll main criteria and two of the
  additional ones are needed for diagnosis.
  (Terho,
  Keuhkosairaudet, Duodecim 20

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EAA, differential diagnostics

• Organic Dust Toxic Syndrome (ODTS)
• Sarcoidosis
• Drug-induced pneumonitis
• Viral and mycoplasma pneumonias
• Tuberculosis
• Allergic bronchopulmonary aspergillosis
• Collagen-vascular diseases
• Lymphangitis carcinomatosa
• Pulmonary fibrosis (DIP)
• Pneumoconioses

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EAA, treatment

• Stopping of exposure
• Oral steroids
• Farmer's lung after recovery back to work
  excluding/minimizing the exposure
• motorized respiratory ventilator, training!
• after reorganization of the job description
• follow-up

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EAA, prognosis

• Continuing exposure, relapsing disease leads to
  pulmonary fibrosis, permanent loss of pulmonary
  function and cor pulmonale.
• When Finnish cases with farmer's lung were
  followed for 10 years, 23 had findings of
  pulmonary emphysema or pulmonary fibrosis.

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EAA, prevention

• reduction of dust exposure
• work hygienic improvements
• adequate respirators always during exposure-
  before any symptoms!
• occupational health care
• information
• follow-up
• finding symptomatic workers in time, to prevent
  permanent loss of pulmonary function

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Organic Dust Toxic Syndrome (ODTS)

• opening of silos pulmonary mycotoxicosis
• exposure to grain grain fever
• 1986 diPico ODTS
• Etiology heavy exposure to biological organic
  dustsmycotoxins and endotoxins
• No sensitization
• No latency time
• prevalence numbers farmers 14 mushroom
  cultivation 37

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ODTS

• Symptoms
• fever, main symptom
• cough
• irratative symptoms of mucous membranes
• fatigue
• myalgia
• Symptoms mild to severe, ceasing when no exposure
• Symptoms milder than in allergic alveolitis
• No chronic form?

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ODTS, diagnostics

• Criteria not yet clear
• Investigated as allergic alveolitis
• Exposure and timing of symptoms important, often
  a few hours after exposure.
• No findings in chest X-ray
• lung function normal or as in EAA but mild
• BAL neutrophilia?
• Work place provocation test following symptoms,
  temperature, diffusion capacity and FEV1/PEF

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Differential Diagnostics Extrinsic allergic
alveolitis (EAA)/Asthma(OA)/ODTS
Feature EAA OA ODTS Symptoms Cough,
dyspnea Cough, dyspnea Flu-like
symptoms fever fever Onset after
exposure Gradual after 4-8h Immediate or Gradual
after 3-8h late Physical findings Bibasil.
crackles Expirat. wheezes None Chest
X-ray Infiltrates/norm. Normal Normal Lung
function Restrictive Obstructive Normal? Peripher
al eosinophilia No Yes? No
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Conclusion

• Farmers lung is the most usual extrinsic
  allergic alveolitis. Chronic form leads to severe
  disability.
• Reduction of the exposure to biological dust by
  work hygienic improvements and using adequate
  respirators is important. The humidifiers and
  other sources of exposure should be cleaned.
• Early recognition of the symptoms is essential.
• ODTS is a milder syndrome, symptoms can be
  prevented using respirator when exposed.

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Literature

• Pickering CAC, Newman Taylor AJ. Extrinsic
  allergic bronchioloalveolitis (hypersensitivity
  pneumonia). In RW Parkes, Occupational Lung
  Disorders, Third edition1994, Butterworth
  Heineman Ltd, UK,
• Terho EO. Orgaanisten pölyjen aihettamat
  keuhkokudoksen yliherkkyysreaktiot. Kirjassa
  Allergologia, toim. Haahtela T, Hannuksela M,
  Terho E.O. Kustannusosakeyhtiö Duodecim,
  1999391-403.
• Terho EO. Allerginen alveoliitti ja sitä
  muistuttavat sairaudet. Kirjassa
  Keuhkosairaudet, toim. Kinnula V. Laitinen L.A.L,
  Tukiainen P. Kustannusosakeyhtiö Duodecim,
  2000336-342.