From the Guidelines
Desquamative Interstitial Pneumonia (DIP) is best diagnosed and monitored through High-Resolution Computed Tomography (HRCT) scans, which typically show diffuse ground glass opacity in the middle and lower lung zones, as this method provides the most accurate assessment of the disease's progression and treatment response. When evaluating DIP, it's crucial to consider the radiological findings in the context of the patient's clinical presentation and history, particularly their smoking status, as DIP predominantly affects cigarette smokers in their fourth or fifth decade of life 1. The chest radiograph may show less severe changes compared to other interstitial lung diseases like IPF and may even be normal in up to 20% of cases, highlighting the importance of HRCT for accurate diagnosis 1.
Key Radiological Features of DIP:
- Diffuse ground glass opacity in the middle and lower lung zones on HRCT scans
- Minimal to no honeycombing or reticular abnormalities
- Bilateral and symmetric distribution, with the lower lobes being more prominently affected
- Small cystic spaces may occasionally be seen within areas of ground-glass opacity
- Lack of significant traction bronchiectasis or architectural distortion
- Pleural effusions are uncommon
These radiological features, as described in the American Thoracic Society's international consensus statement 1, are critical for differentiating DIP from other interstitial lung diseases, such as usual interstitial pneumonia (UIP), which tends to show more severe reticular opacities and honeycombing with a subpleural distribution. The distinction is important due to the better prognosis associated with DIP compared to UIP, with an overall survival of about 70% after 10 years when appropriately managed 1.
Clinical Implications:
- Early diagnosis through HRCT is vital for initiating appropriate treatment and improving patient outcomes.
- Serial imaging is necessary for monitoring disease progression and response to treatment.
- Smoking cessation is a critical component of managing DIP, given its strong association with cigarette smoking 1.
By prioritizing HRCT scans and considering the clinical context, healthcare providers can effectively diagnose and manage DIP, ultimately improving patient morbidity, mortality, and quality of life.
From the Research
Desquamative Interstitial Pneumonia (DIP) Radiology
- DIP is a rare form of idiopathic interstitial pneumonia (IIP) with characteristic features on high-resolution computed tomography (HRCT) scan, including bilateral ground-glass opacities with lower lobe predominance (92%) 2.
- Radiological findings may also include ground glass opacities and/or consolidation, with one third of patients showing thin-walled cysts within the ground glass opacities 3.
- In some cases, DIP may progress to lung fibrosis, characterized by the development of new thin-walled cysts and honeycombing on HRCT scans, despite therapy 3.
- High-resolution computed tomography (HRCT) is useful in assessing the long-term radiological follow-up results in patients with DIP, and may show progression to lung fibrosis in some cases 3.
- Other radiographic features of DIP and related conditions, such as respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), may include reticulonodular and ground glass opacities, centrilobular nodules, thickening of bronchial walls, and a reticular pattern 4.