Pulmonary Alyeolar Microlithiasis:Systemic Review Of72Patients In China

Objective In order to improve the diagnosis and treatment level of pulmonary alveolar microlithiasis (PAM), we have analyzed clinical data (clinical presentations, laboratory tests, imaging features, etc.) of domestic existing cases confirmed by pathology, and foreign literatures have also been reviewed.Methods The details of one case of PAM treated at the second affiliated hospital of Zhejiang University medical college was retrospectively analyzed and reviewed together with those of71cases previously reported from the literature which were all confirmed by pathology.Results Among the72patients,44cases were male(61.1%), and28cases were female(38.9%). Median age was29. Additionally, there were30cases having family history and they came from25families, furthermore, being siblings of one another. Course of disease when diagnosed was ranging from29days to8years. These patients came from20provinces of China. The clinical presentations of most patients were none or mild. Common clinical features included cough (43/72,59.7%), tachypnea (33/72,45.8%), expectoration (24/72,33.3%), cough with stone (16/72,22.2%), chest distress (12/72,16.7%), and chest pain (10/72,13.9%). Positive Signs mainly included moist rales and barrel chest, which in fact were clinically rare. Few of patients were reported to have long-term history of smoking and dust exposure. Complications included pulmonary hypertension, pulmonary heart disease, respiratory failure, pneumothorax, pulmonary interstitial fibrosis, interstitial pneumonitis, chronic bronchitis, pneumonia, lung abscess, fibrinous pleurisy with organization and adhesions, upper respiratory tract infection, Bronchioloalveolarcarcinoma, rheumatoid arthritis, viral encephalitis, and multiple cerebral infarction.17cases had results of serum calcium and phosphate level tests, which remained normal.17cases had been taken blood-gas analysis, among them there were one case with hypoxemia,4cases with type I respiratory failure and1case with type II respiratory failure.34cases had been assessed with their pulmonary function:15of them turned out to be normal;5of them had combined ventilation dysfunction;2of them had obstructive ventilation dysfunction;4of them had restrictive ventilation dysfunction. And all of the above had combined with diffusion dysfunction.1of them had combined ventilation dysfunction;2of them had obstructive ventilation dysfunction;4of them had restrictive ventilation dysfunction;1of them had diffusion dysfunction, and the rest of them were normal.14cases had been taken ECG examination:8of them showed axis leaning right, which meant right ventricular hypertrophy,1of them showed sinus tachycardia.62cases had been taken X-ray chest film examination, of which only1(1.6%) case was normal in this examination.55(95.2%) of them showed bilateral, small miliary nodulars, the margin of the nodular was clear and the density of the nodular was very high.4(6.5%) of them showed typical changes of "snowstorm".1(1.6%) of them showed lung marking thickening. Multiple patchy shadows were presented in1(1.6%) of them. In all of the62patients, other accompany appearances included declination of lucency in both lungs (10cases,16.1%), pleural thickening (6cases,9.7%), calcification of pericardium and pleural (4cases,6.5%).41cases taken CT scanning, of which only1(2.4%) case was normal in this examination.39(95.1%) of them showed bilateral, small miliary nodulars.16(39.0%) of them showed pleural thickening and calcification.12(29.3%) of them showed ground-glass like changes.9(21.9%) of them accompanied with pulmonary interstitial fibrosis.8(19.5%)of them showed signs of "flame" or "white line".1(2.4%) of them showed space occupying lesions in left upper lobe.33patients had been misdiagnosed as other diseases, common misdiagnosing diseases were phthisis miliaris (37.5%)、 silicosis(5.6%)、bronchopneumonia(1.4%)、pulmonary alveolar proteinosis (1.4%). The72patients were all confirmed by pathology.37(51.4%) of them were proven by Bronchoscopy,6(8.3%) of them were proven by TBLB,4(5.6%) of them were proven by BAL,12(16.7%) of them were proven by sputum with sand-like materialsn confirmed calcium,4(5.6%)of them were proven by open lung biopsy,4(5.6%)of them were proven by transdermal acupuncture biopsy,3(4.2%) of them were proven by thoracoscope biopsy and2of them were proven by autopsy. Treatments were described in14cases,5of them accepted bronchoalveolar lavage, among them,3cases flushed out sand-like materials, but only1case had improved in his X-ray films,1of them had no changes and1of them became worse and effects of the rest2cases were not mentioned. Other treatments included symptomatic therapies and supportive therapies such as oxygen uptaking, spasmolysis, relieving cough, eliminating sputum and antibiotics. During the follow-up period,2cases died. One person died for heart failure and septic shock, and the other person died for respiratory failure and gluteal region infection.Conclusion PAM is a rare genetic lung disorder without specific clinical features, therefore PAM is easily misdiagnosed. In Chinese population, the incidence is higher in age brackets between20and30years. Diagnosis should be suspected on chest imaging which is almost pathognomonic. Detection of calcium deposits in pathological examination further supports the clinical and radiological diagnosis. So far, there have been no effective treatments. The main treatments include preventing from infection and keep away from smoking and dust, and lung transplantations are considered as ultimate choices for the end-stage PAM patients. The prognosis of PAM is poor.