Lung Function Decline in Pulmonary Alveolar Microlithiasis

Pulmonary alveolar microlithiasis (PAM) is a rare lung disorder characterized by calcium phosphate microliths in the alveolar spaces. Autosomal recessive mutations on the SLC34A2 gene lead to altered type IIb sodium phosphate cotransporter in alveolar type-II cells of the lung, thus resulting in aggregations of microliths in the alveoli. To date, more than 1000 cases have been reviewed by expert pulmonary clinicians. PAM is observed worldwide, with numerous cases reported in Asia and Europe. It generally progresses slowly, with symptoms commonly emerging during an individual's third or fourth decade of life. Dissociation between the clinical picture and the radiological pattern is usual. Computed tomography (CT) may show extensive radiological disease even in patients with minimal clinical symptoms. The decline in lung function is typically progressive; however, detailed information regarding specific spirometry changes remains insufficient and largely unknown. PAM management is basically supportive using vaccines, antibiotics in recurrent infections, or long-term oxygen when respiratory failure is determined. A bilateral lung transplant may be a resolutive treatment for end-stage disease. We report a lung function decline of a familial case of PAM in a 71-year-old female patient at our Interstitial Lung Disease Clinic.