Update on diagnosis and treatment of pulmonary alveolar microlithiasis

摘要

Pulmonary alveolar microlithiasis(PAM)(MIM265100)is a rare disease characterized by the diffuse deposit of microlithiasis in alveolar spaces.PAM could occur worldwide with high prevalence in Asia and Europe.Familial occurrence indicates its autosomal recessive trait and the SLC34A2 gene was identified as the responsible gene for the disease.In spite of the versatile mutation sites in patients from other countries,exon 7and exon 8 might be the most liable gene in Chinese and Japanese patients.Most mutations caused the premature termination of proteins and produced truncated proteins,leading to the blocking of the recycling and degrading of outdated surfactant which is full of phospholipids.The most outstanding clinical feature of PAM is the discrepancy between the paucity of symptoms and the degree of pulmonary involvement.Diagnosis is easy to establish based on typical chest radiograph image and nuclear medicine improves its early diagnosis and active evaluation.Pathology of the unique intra-alveolar lamellar microliths gives strong support for diagnosis.No effective treatment is considered valid currently.However,lung transplantation is effective for advanced-stage patients,and long term treatment of disodium etidronate seems promising.