A 48yo farmer presented with fever, malaise, cough and SOB. Exam: tachypnea, coarse inspiratory crackles and wheeze throughout, cyanosis. Also complains of severe weight loss. His CXR shows fluffy nodular shadowing. There is also PMN leukocytosis. What is the single most appropriate dx?
a. Ankylosing spondylitis
b. Churg-strauss syndrome
c. Cryptogenic organizing
d. Extrinsic allergic alveolitis
e. Progressive massive fibrosis
answer: D
HYPERSENSITIVITY PNEUMONITIS
• also known as extrinsic allergic alveolitis
• non-IgE mediated inflammation of lung parenchyma (acute, subacute, and chronic forms)
• caused by sensitization to inhaled agents, usually organic dust
• pathology: airway-centered, poorly formed granulomas and lymphocytic inflammation
• exposure usually related to occupation or hobby
Farmer’s Lung (Thermophilic actinomycetes)
Bird Breeder’s/Bird Fancier’s Lung (immune response to bird IgA)
Humidifier Lung (Aureobasidium pullulans)
Sauna Taker’s Lung (Aureobasidium spp.)
Signs and Symptoms
• acute presentation: (4-6 h after exposure)
dyspnea, cough, fever, chills, malaise (lasting 18-24 h)
CXR: diffuse infiltrates
type III (immune complex) reaction
• chronic presentation
insidious onset
dyspnea, cough, malaise, anorexia, weight loss
PFTs: progressively restrictive
CXR: predominantly upper lobe reticulonodular pattern
type IV (cell mediated, delayed hypersensitivity) reaction
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