Crazy Paving in Pulmonary Alveolar Proteinosis
Brian W. Allwood and Sami Bennji
N Engl J Med 2020; 382:275
DOI: 10.1056/NEJMicm1908563
A 34-year-old man with a 20-pack-year smoking history presented to the emergency department with a 4-month history of progressively worsening dyspnea and nonproductive cough. The oxygen saturation was 65% while the patient was breathing ambient air. He appeared to have dyspnea at rest, his fingers and lips were blue, and his fingers showed clubbing. Sounds on auscultation of the lungs were normal. Computed tomography of the chest revealed diffuse ground-glass opacities with interlobular and intralobular septal thickening — a pattern described as crazy paving (Panel A). Bronchoscopy yielded milky-appearing lavage fluid, and pathological testing showed macrophages filled with proteinaceous material that was positive on periodic acid–Schiff staining, as well as large acellular eosinophilic aggregates. These findings confirmed a diagnosis of pulmonary alveolar proteinosis, which is caused by impaired surfactant turnover. Crazy paving is not pathognomonic of pulmonary alveolar proteinosis and can be seen in a number of other conditions, including acute respiratory distress syndrome, lipoid pneumonia, organizing pneumonia, pulmonary hemorrhage, and Pneumocystis jirovecii pneumonia. The patient underwent large-volume lavage of both lungs in sequential procedures, with the use of 15 liters of saline in each lung. Panel B shows, from left to right, the appearance of the lavage fluid from the right lung after the infusion of 1, 3, 5, and 15 liters of saline. At follow-up 6 months later, the patient had substantial improvement in his clinical condition, with oxygen saturation of 92% while he was breathing ambient air.
一名34岁男性患者有吸烟史20包年，因呼吸困难及干咳进行性加重4个月到急诊科就诊。患者吸空气时氧饱和度65%。静息状态下患者即表现呼吸困难，手指及口唇紫绀，且有杵状指。双肺听诊呼吸音正常。胸部CT提示弥漫性磨玻璃样改变，伴小叶间和小叶内间隔增厚—即碎路石征(crazy paving) (图A)。支气管镜吸出牛奶样灌洗液，病理检查发现巨噬细胞内充满蛋白样物质，过碘酸Schiff染色阳性，且有较大的无细胞嗜酸性物质。根据上述表现确诊为肺泡蛋白沉积症，该病由表面活性物质代谢异常引起。碎路石征并非肺泡蛋白沉积症的特异性表现，可见于其他疾病，包括ARDS，脂质肺炎，机化性肺炎，肺出血和肺孢子虫肺炎。患者接受双肺大量灌洗，每侧肺灌洗生理盐水 15 L。图 B 从左至右分别为灌洗1，3，5和15 L生理盐水后的灌洗液。6个月后随访时，患者临床情况显著改善，吸空气时氧饱和度 92%。
