The condition may progress, remain stable, or clear spontaneously. Most patients present with gradually progressive exertional dyspnea and cough that is usually unproductive. Those who smoke cigarettes usually produce sputum. Sputum characteristics are generally unhelpful. Although the patient may present with or soon after a febrile illness, persistent fever is rare unless secondary infection occurs.
Extrapulmonary symptoms are unusual.
Physical findings are limited to the lungs but may be absent despite diffuse parenchymal involvement visible on chest x-ray. Fine inspiratory crackles are usually heard over the affected lung areas. Diagnosis Specific diagnosis requires a lung biopsy or bronchoscopy with segmental bronchoalveolar lavage. The latter requires special staining techniques. Characteristic findings in tissue and lavage fluid are seen by light or electron microscopy.