RESUMO
Pulmonary alveolar microlithiasis (PAM) is a rare genetic disease characterized by calcifications within the alveoli in the lung. Mutations in SLC34A2 gene, which encodes a type IIb sodiumphosphate cotransporter, are responsible for PAM, leading to the intra-alveolar accumulation of phosphate which favors the formation of microliths. A "sandstorm" appearance is the typical radiographic presentation of PAM. The hallmark of this disorder is clinical-radiological dissociation, with typical imaging findings, specific pathological findings and closely correlated specific genetic mutations. The disease has an insidious onset, runs a chronic course and the prognosis is poor. There is no effective treatment except for lung transplantation. This article summarizes the epidemiology, molecular genetics and clinical features of pulmonary alveolar calculi.