Bony lesions may occur in the ribs or any other bone. Honeycombing indicates advanced disease. Hilar or mediastinal adenopathy is rare. Lung volume often is preserved and can be increased. The diffusing capacity for carbon monoxide generally is reduced.
Some patients have reversible airflow limitation.
Gas exchange abnormalities may be present at rest. Pulmonary exercise testing may demonstrate decreased exercise capacity, with reduced oxygen utilization. Gas exchange, ventilatory, and pulmonary vascular irregularities, as well as and metabolic abnormalities also may be present. Exercise limitation generally is multifactorial. The total recovery of all cell types usually is increased with a cell differential that includes increased absolute numbers of neutrophils, eosinophils, and lymphocytes.