Chest Imaging

Desquamative interstitial pneumonia

(DIP), nonspecific reaction of lung to injury, characterized histologically by the presence of numerous macrophages filling alveoli, mild inflammation of alveolar walls, and minimal fibrosis. DIP can be seen in patients with a variety of infiltrative lung diseases, including idiopathic pulmonary fibrosis, collagenvascular diseases, histiocytosis X pulmonary, and drug reactions. Patients with DIP have milder symptoms, a better prognosis, and respond better to treatment with corticosteroids than do patients with usual interstitial pneumonia (UIP); 5-year mortality is only 5% in patients with DIP, as compared to 45% in patients with UIP.

The most common finding on chest radiographs in patients with DIP is the presence of ground-glass opacities in the lower lung zones. However, in up to 20% of patients with biopsy-proven DIP, the chest radiograph is normal. On HRCT, the predominant abnormality is the presence of patchy ground glass opacity. Opacities may have a lower lobe or peripheral predominance in some patients. Irregular linear opacities and architectural distorsion, indicating the presence of fibrosis are present in about half of patients, and honeycombing may also be seen but is less common.

RW