肺泡微石症一例并文献复习

Pulmonary alveolar microlithiasis: case report and literature review

目的提高对肺泡微石症(PAM)的认识。方法通过胸部影像学将男性患者及其兄考虑为PAM,行基因测序检查,通过经皮肺穿刺活检确认诊断。在PubMed上搜索并获得了108篇国外文献,共172例患者,分析、归纳该病的临床表现、影像学特点、病理学特征、诊断及鉴别诊断、治疗及预后。结果基因测序结果显示,患者及其兄SLC34A2基因第8外显子存在c.910A>T的纯合突变。磷酸钠共转运蛋白Npt2b的SLC34A2基因突变是PAM主要的发病机制,中国人最常见的是第8外显子发生突变。最常见的症状是呼吸困难,其次为咳嗽、胸痛、发热、疲劳、咯血。临床体征主要有口唇紫绀、杵状指、听诊两肺闻及细湿罗音或者Velcro啰音。胸部X线片常呈"沙尘暴"征,胸部CT表现为双肺弥漫性高密度微结节影,可呈特征性的钙化影。肺活检病理示肺组织内可见微石,微石由钙质同心薄片组成。口服依替膦酸二钠的疗效有限,肺移植是最终的有效治疗方法。结论 PAM是一种罕见的常染色体隐性遗传性肺病。应充分认识该病的有关特点,以期做到早期诊断、早期干预。晚期患者建议行肺移植。

Objective To improve the understanding of pulmonary alveolar microlithiasis(PAM). Methods A male patient and his brother were considered PAM by chest image and further examined by gene sequencing. The patient was confirmed through percutaneous lung biopsy. The clinical data of 172 patients from 108 pieces of literature were collected and reviewed from PubMed. The clinical presentation, radiological character, pathological finding, diagnosis and differential diagnosis, treatment and prognosis of the disease were analyzed and summarized. Results The results of gene sequencing revealed the homozygous mutation of c.910 A>T in exon 8 of SLC34A2 gene. The genetic mutation encoding the sodium phosphate co-transporter Npt2 b(SLC34A2) was considered as the major pathogenesis.Mutations appeared to cluster in exon 8, c.910 A>T was the most common mutation observed in Chinese cases. The most obvious symptoms were dyspnea, followed by cough, chest pain, fever, fatigue, and hemoptysis. The clinical signs consisted of cyanosis, clubbed fingers, moist rales and velcro crackles in the lungs. The typical presentation of PAM on a chest X ray was a ‘sandstorm’ appearance. The most frequent high-resolution CT findings of PAM were diffuse ground-glass attenuation and subpleural linear calcifications. Lung biopsy showed lamellar microliths deposited in alveolar spaces and the pleura. Etidronate had an imprecise role in the treatment of PAM. Lung transplantation was the ultimate effective treatment option. Conclusions PAM is a rare autosomal recessive inherited lung disease. The characteristics of the disease should be fully understood in order to achieve early diagnosis and early intervention. Lung transplantation is recommended for patients of end stage.