HYPERSENSITIVE PNEUMONITIS (Extrinsic allergic alveolitis, EAA)

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HYPERSENSITIVE PNEUMONITIS(Extrinsic allergic
alveolitis, EAA)

• MORONIKE OLUBUKOLA AJOKE
• GROUP 501
• INTERNATIONAL MEDICAL FACULTY

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Hypersensitivity pneumonitis definition

• Hypersensitivity pneumonitis is a spectrum of
  granulomatous, interstitial, and alveolar-filling
  lung diseases that result from repeated
  inhalation of and sensitization to a wide variety
  of organic dusts.

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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

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EAA

• Pathology Granulomatous inflammation around the
  alveoli and the peripheral bronchioles.Exudate
  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
  disappears in 3-4 months.
• If the exposure continues, the exudation
  organizes into fibrin and an irreversible
  pulmonary fibrosis follows.

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Mushroom Workers Lung (Thermoactinomyces
vulgaris)
Acute onset of fever, malaise, and shortness of
breath after spawning Chest diffuse crackles
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Hypersensitivity pneumonitis (HP)Diagnosis

• Diagnosis of HP
• - Compatible clinical picture (symptoms, chest
  x-ray or CT, lung function changes) of HP
• - Presence of precipitating antibodies
• - Bronchoalveolar lavage
• - Lung biopsy
• Objective testing to establish work-relatedness
• - Returning to work induce similar symptoms and
  signs
• - Specific challenge tests more difficult to do.

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Hypersensitivity pneumonitis - microorganisms (1)
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Hypersensitivity pneumonitis - microorganisms (2)
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Hypersensitivity pneumonitis (3)
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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
  chronic form digital glubbing
• Chest X-ray normal or small nodules, diffuse
  infiltrates, ground
• glass appearance, chronic
  form pulmonary fibrosis
• HRCT normal or ground glass appearance centri
  lobular micronodules
• Lung function restriction, diffusing capacity
  decreases, hypoxemia, obstruction,
  hyperreactivity
• Lab. tests rise of ESR, leukocytosis,
  neutrophilia
• BAL 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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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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• Diagnosis of Hypersensitivity pneumonitis
• Lab Tests
• May have increased inflammatory markers
  (erythrocyte sedimentation rate, C-reactive
  protein)
• Leukocytosis and increased gamma globulins
  typically seen
• Specific IgG antibody to offending agent can be
  detected and checked serially to detect response
  to treatment
• Not always present (likely because many unknown
  antigens)
• Low specificity (10 of people exposed to
  farmers lung antigen develop antibodies only
  0.3 show symptoms)
• Rheumatoid factor often positive (unknown cause)
• Negative blood, sputum, throat cultures
• Bronchoalveolar lavage (BAL)
• - Acute form with neutrophils and CD4 T
  lymphocytes
• - Chronic form with high number of CD8 T
  lymphocytes
• - BAL may help to differentiate chronic
  hypersensitvity pneumonitis from sarcoid, which
  has high CD8 T lymphocytes
• - Neutrophilia, lymphopenia, increased ESR, C
  reactive protein, rheumatoid factor, raised serum
  immunoglobulins.

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• Diagnosis of Hypersensitivity pneumonitis
• Chest x-ray
• Acute Diffuse ground-glass infiltrates, nodular
  or striated patchy opacities. Up to 20 have
  normal CXR.
• Subacute Same as acute, may have sparing of lung
  bases
• Chronic Upper lobe fibrosis, reticular
  opacities, volume loss, honeycombing
• may be normal or show patchy or diffuse
  infiltrates or discrete nodular infiltrates.
  There may be honey-combing.
• CT scanning
• is diagnostic showing the details of fibrosis,
  and nodules.

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• Diagnosis of Hypersensitivity pneumonitis
• Pulmonary function test (PFT)
• shows a restrictive or obstructive pattern,
  decreased lung volume, impaired diffusion
  capacity, bronchial hyper reactivity and
  reversibility.
• BAL (Bronchoalveolar lavage)
• shows lymphocytic alveolitis.
• Lung biopsy through bronchoscopy may be
  diagnostic.
• Inhalation challenge i.e. a positive response to
  inhaled antigen may be done for transient
  airflow obstruction.

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Treatment of Hypersensitivity pneumonitis

• The condition should be diagnosed by
  occupational history, lifestyle, livelihood, Hlo
  exposure to antigens .
• The exposure should be checked by wearing of
  appropriate masks, pollen masks, personal dust
  respirators, air helmets, ventilated helmets with
  fresh air.
• Glucocorticoids Prednisone 1 mg/kg/day for 1-2
  weeks. Maintenance dose may be continued at the
  lowest possible dosage if symptoms recur.
• Avoidance of offending antigen is primary
  therapy.
• Corticosteroids
• Prednisone 12 mg/kg/day, to max of 5060 mg
  p.o. daily
• Initial course of 12 weeks with progressive
  taper
• Low-dose therapy (20 mg p.o. daily) may be as
  effective as avoidance

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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
  exposurebefore 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 ODTSEtiology of ODTS heavy
  exposure to biological organic dusts, mycotoxins
  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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