Purpose of review: Our knowledge of pulmonary alveolar microlithiasis (PAM) has significantly increased since its detailed description by Sosman in 1957. Here we provide updated information on the long-term clinical course, the specific findings in imaging studies and the genetics of this disease.
Recent findings: The responsible gene, the mutation of which is associated with PAM, has been identified as SLC34A2. Characteristic chest computed tomography (CT) findings in patients with PAM have been shown to correlate well with specific pathological findings. Elevated serum levels of surfactant proteins A and D have also been reported in this disease. Long-term follow up information has been updated.
Summary: The gene responsible for PAM, SLC34A2, has been identified. It encodes a type IIb sodium-dependent phosphate transporter, the function of which provides an insight into the pathogenesis of this disease. The demonstration of a mutation in the SLC34A2 gene helps to confirm the diagnosis of PAM. Characteristic chest CT findings that include irregular thickening of perilobular interstitium and calcification along perilobular structures correlate with specific pathological findings. Serum levels of surfactant proteins A and D correlate with the progression of the disease, and may be a useful monitoring tool. Scrutiny of the long-term follow-up data of PAM patients reveals that the prognosis for PAM is poor. The establishment of an effective treatment, which is not yet available, is mandatory.