Surgical lung biopsy showing diffuse alveolar damage in the absence of known causes of ARDS and diffuse alveolar damage (eg, sepsis, drugs, toxins, radiation, viral infection) confirms a diagnosis of AIP. [merckmanuals.com]

Acute interstitial pneumonia (AIP), a form of idiopathic interstitial pneumonia, equally affects apparently healthy men and women, usually those > 40 years. [merckmanuals.com]

Fever, cough, and difficulty breathing develop over 1 to 2 weeks, typically progressing to acute respiratory failure. [merckmanuals.com]