대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Desquamative Interstitial Pneumonia

Radiologic Findings

Chest PA shows ground-glass opacity in both lower lung fields. Magnified image shows diffuse reticular opacities in left lower lung fields. Cross-sectional high-resolution CT images of the both lower lung zone show diffuse bilateral ground-glass attenuation. Note cystic spaces within the subpleural areas of ground-glass attenuation. Pulmonary architecture and pulmonary vessels through the cystic lesions are still preserved and not distorted.

Open lung biopsy specimen of the patient shows inflammation of the alveolar interstitium with relative preservation of the alveolar anatomic structure and the presence of many macrophages within the alveolar air spaces, which is typical for DIP.

Brief Review

Desquamative interstitial pneumonia (DIP) is subtype of the idiopathic interstitial pneumonia and often grouped with usual interstitial pneumonia within the spectrum of idiopathic pulmonary fibrosis. However, recent studies revealed that DIP differs from usual interstitial pneumonia in its histologic appearance, radiologic findings, and, most importantly, its natural course. Approximately 90% of patients with DIP are cigarette smokers. Most cases of DIP are currently considered to represent a reaction to cigarette smoke.
The most common finding on the chest radiograph is the presence of ground-glass opacity in the lower lung zones. The most common findings on HRCT in patients with DIP are ground-glass attenuation with lower lobe and subpleural predominance. A mild reticular pattern is present in approximately 50% of patients. Irregular lines of attenuation, cystic changes, and traction bronchiectasis may also be seen but are usually not prominent. Architectural distortion, traction bronchiectasis and micronodules are probably a reflection of associated respiratory bronchiolitis. An unusual CT finding seen in some patients with DIP is small cysts. These differ from honeycomb cysts in that they occur in areas not involved with fibrosis and may resolve on follow-up CT.
Histologically, DIP is characterized by mild inflammation of the alveolar interstitium with relative preservation of the alveolar anatomic structure and the presence of many macrophages within the alveolar air spaces. Akira et al.reported that open lung biopsy samples from patients with DIP with many cystic lesions showed dilated alveolar ducts and bronchiole and/or pulmonary cyst as well as numerous macrophage-filled air spaces and mild fibrosis, but no typical honeycomb cysts were seen.
The combination of cysts and ground-glass attenuation should suggest the diagnosis of DIP.

References

1. Lee KH, Lee JS, Lynch DA, et al. The radiologic differential diagnosis of diffuse lung diseases characterized by multiple cysts or cavities. J Comput Assist Tomogr. 2002 ;26:5-12.
2. Akira M, Yamamoto S, Hara H, et al. Serial computed tomographic evaluation in desquamative interstitial pneumonia. Thorax 1997 Apr;52:333-7
3. Hartman TE, Primack SL, Swenwen SJ, et al. Desquamative interstitial pneumonia: thin-section CT findings in 22 patients. Radiology 1993;187:787-790.

Keywords

Lung, Idiopathic interstitial pneumonia, DIP, smoking related, IIP,