【影像征象】铺路石征 | The crazy-paving sign

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The crazy-paving sign is a pattern seen on thin-section computed tomographic (CT) images of the lungs. It is characterized by a reticular pattern superimposed on ground-glass opacity (Figure). The term crazy-paving is used because the sign resembles the appearance of paths made with broken pieces of stone or concrete.
铺路石征是胸部薄层CT上的一种征象，以磨玻璃影上重叠有网格影为特征。铺路石征因形似于石头或混凝土碎片铺成的道路而广泛使用。

图1 

Explanation

In the crazy-paving sign, ground-glass opacity may reflect the presence of airspace or interstitial abnormalities; the lines of reticular opacities may represent interlobular septal thickening, thickening of the intralobular interstitium, irregular areas of fibrosis, or a preponderance of an airspace-filling process at the periphery of lobules or acini.
在铺路石征中，磨玻璃影反映空腔或间质性异常；网格影表示小叶间隔增厚、小叶内间质增厚、不规则纤维化，或周边小叶或腺泡边缘以空腔填充过程为主。

Discussion

The crazy-paving sign was initially recognized in patients who had pulmonary alveolar proteinosis(PAP). 
铺路石征最初见于肺泡蛋白沉积症患者。

PAP manifests as filling of the alveoli by a proteinaceous material that is rich in lipids, in association with an inflammatory response in the adjacent interstitium. It is believed that PAP results from an abnormality of surfactant production, metabolism, or clearance by type II alveolar cells and macrophages. 

其表现为肺泡内富磷脂蛋白样物质充盈，伴有邻近炎性反应。PAP是由于II型肺泡细胞和巨噬细胞表面活性物质产生、代谢或清除障碍引起的。

Most cases are idiopathic.

多数病例是特发性的。

The linear network or reticular pattern in the crazy-paving sign is believed to result from a thickening of the interlobular septa, while areas of ground glass opacity result from partial alveolar filling processes. Interlobular septal thickening can be seen from interstitial fibrosis, but the presence of areas of reticular opacity does not necessarily represent interstitial abnormalities.
铺路石征中的线性网状影或网格影是由于小叶间隔增厚引起，而磨玻璃影则是由于部分肺泡的填充。间质纤维化也可见小叶间隔增厚，但网格影不一定代表间质异常。

When there is a slight increase in the severity of the alveolar filling process at the borders of unit structures such as acini or secondary pulmonary lobules, the networks in the crazy-paving sign can also be caused purely by airspace disease.
当腺泡或次级肺小叶边界处肺泡严重填充且稍有增加时，铺路石征中网格影也可由空腔性疾病引起。

The crazy-paving sign may also be seen in patients with a variety of other diseases. The differential diagnosis of crazy-paving sign includes Pneumocystis carinii pneumonia, mucinous bronchioloalveolar carcinoma, sarcoidosis, lipoid pneumonia, adult respiratory distress syndrome, and pulmonary hemorrhage syndromes.
其他各种疾病也可见铺路石征。铺路石征的鉴别诊断包括肺孢子虫肺炎、粘液性细支气管肺泡癌、结节病、类脂性肺炎、成人呼吸窘迫综合征和肺出血综合征。

其他包括间质性肺炎、急性放射性肺炎和药物性肺炎。

参考文献

  1.Lee C H. The crazy-paving sign.[J]. Radiology, 2007, 243(3):905-6.

2.Yudin A. Crazy-Paving Sign[M]// Metaphorical Signs in Computed Tomography of Chest and Abdomen. Springer International Publishing, 2014:13-13.

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