Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis can present in acute, subacute, or chronic forms. The case described includes two episodes of the acute form. The patient was exposed to mold antigens in his flooded home. Within 4–8 hours of exposure, chills, cough, and shortness of breath will be noted, and at times will be dramatic. A chest film can be normal, even with significant hypoxia. Pulmonary function tests will show restrictive changes, as compared to the reversible obstructive changes of acute asthma. Blood tests often show an elevated erythrocyte sedimentation rate. Serum IgG tests for the probable antigen confirm the diagnosis.

Symptoms of acute hypersensitivity pneumonitis resolve over several days, but will suddenly and violently recur with repeated exposure to the offending antigen. The subacute form begins gradually over weeks or months, causing a cough and increasing shortness of breath. The chronic form develops over years of exposure, causing fibrotic changes to the lungs that will be evident on radiographs, as well as chronic crackles on auscultation.” ABFM

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