Pulmonary alveolar microlithiasis: report of two brothers with the same illness and review of literature.

Pulmonary alveolar microlithiasis (PAM) is a rare lung disease characterised by extensive deposition of calpospherites within the alveoli. The disease is caused by mutations in the gene SLC34A2 encoding sodium-dependent phosphate co-transporter. It is an autosomal recessive disease with sporadic cases worldwide. Most patients are asymptomatic at the time of diagnosis. It may progress slowly over years to respiratory failure and cor pulmonale.