肺间质病变与肺实质病变并存而很少单独存在,不同疾病累及肺间质及肺实质的程度不同。故本文所谓肺间质病变,系指以间质改变为主的病变而言。间质病变受累的范围可以是局限的,也可是弥漫性的。后者在X线诊断方面易于混淆,且不易根据X线表现推论其原因。究其原因有二:1、其X Pulmonary interstitial disease and lung parenchymal disease co-exist rarely exist alone, different diseases involving the lung interstitial and pulmonary parenchyma to varying degrees. Therefore, the so-called interstitial lung disease in this article refers to the change of the main interstitial lesions. The extent of interstitial disease involvement can be limited, but also diffuse. The latter in the X-ray diagnosis is easy to confuse, and not easy to infer the reason based on X-ray findings. There are two reasons for this: 1, the X.