Pulmonary alveolar microlithiasis. A review including ultrastructural and pulmonary function studies

Area of Science:

• Pulmonology
• Rare Diseases
• Radiology

Background:

• Pulmonary alveolar microlithiasis (PAM) is a rare interstitial lung disease.
• Characterized by diffuse deposition of calcium phosphate microliths in the alveoli.
• Etiology remains largely unknown.

Purpose of the Study:

• To present the Mayo Clinic experience with 8 patients diagnosed with PAM.
• To add to the existing global case reports (approx. 120).
• To review clinical characteristics, diagnostic findings, and disease progression.

Main Methods:

• Review of 8 patient cases from Mayo Clinic.
• Analysis of worldwide literature on approximately 120 reported cases.
• Evaluation of diagnostic imaging (chest roentgenograms), pulmonary function studies, and specialized analyses (Technetium-99m scanning, transmission electron microscopy).

Main Results:

• The disease affects a wide age range (newborn to 80 years), with a mean age at diagnosis around 35 years.
• No sexual predilection observed; familial occurrence noted in about 50% of cases.
• Disease progression is typically very slow, with some patients stable for over 30 years. Pulmonary function studies often show a restrictive pattern.

Conclusions:

• Pulmonary alveolar microlithiasis is a rare, slowly progressive lung disease diagnosed via characteristic radiographic findings.
• No definitive treatment exists; management focuses on supportive care.
• Advanced imaging and microscopy aid in the analysis of pulmonary microliths.