HypersensitivityPneumonitisHypersensitivityPneumonitis

Hypersensitivity Pneumonitis

Definition

Clinical findings

Radiographic appearance

Differential diagnoses

Prognosis

Immunologically mediated

Inhaled organic antigens

<5 micrometers

Type III and type IV responses

Hypersensitivity PneumonitisDefinition

  Onset:4-6 hours after exposure

  SX: Cough, dyspnea, chills, fever

  Duration: 2-5 days

  PFT’s: Restrictive pattern

  Histopathology: Granulomatous interstitialand alveolar pneumonitis

Hypersensitivity PneumonitisAcute

SX:  Prominent dyspnea, fatigue, anorexia,significant weight loss

PFT’S: Obstructive pattern

+/- Interstitial fibrosis

Hypersensitivity PneumonitisChronic

Usually normal

Abnormalities often subtle

Granulomas too small, too few to be seen

Miliary nodulation

Ground glass opacities

ILO Classification

Hypersensitivity PneumonitisFindings

Acute: lower zones of lung

Pulmonary edema

Fine nodular opacities

Thickened hila

Chronic: upper zones of lung

Pulmonary emphysema

Interstitial fibrosis

Hypersensitivity PneumonitisX-ray

Silo filler’s disease (nitrogen dioxide)

Organic dust toxicity syndrome(endotoxin)

Sarcoidosis

Hypersensitivity PneumonitisDDX

Acute: Resolution possible

PFT’s may show persistent decrease infunction

Chronic: Up to  9% long term mortality

Permanent roentgen and pathologic changes

Hypersensitivity PneumonitisPrognosis

Farmer’s Lung

Thermoactinomyces vulgaris in moldy hay

Bird-fancier’s Lung

From protein in pigeon droppings/feathers

Mushroom Worker’s Lung

From mushroom compost

Bagassosis

From moldy sugar cane in sugar mill

Hypersensitivity PneumonitisSpecific Antigens

Malt Worker’s Lung

From malt dust (aspergillus clarvatus)

Maple Bark Disease

From moldy maple bark in saw mill

Suberosis

From moldy cork dust (penicillum frequentans)

Pandora’s Pneumonitis

From forced air heating/AC equipment

Thermophilic actinomycetes

Hypersensitivity PneumonitisSpecific Antigens