Pulmonary alveolar microlithiasis is rare disease characterized by accumulation of calcium phosphate microlithis in the alveoli. The pathogenesis relates to mutation in the gene SLC34A2 (solute carrier family 34 member 2) located on chromosome 4p15.2, which produces a defective sodium-phosphate cotransporter in alveolar epithelial type-2 cells, making these cells unable to clear phosphorus released during recycling of surfactant.
Alkhankan E, Yamin H, Bukamur H, Alkhankan F, Shweihat Y, Zeid F. Pulmonary alveolar microlithiasis diagnosed with radiography, CT, and bone scintigraphy. Radiology case reports. 2019 Jun 1;14(6):775-7.