CASE 740 Published on 21.06.2001

Pulmonary alveolar microlithiasis


Chest imaging

Case Type

Clinical Cases


G. Papamastorakis, A. Voloudaki, M. Daskalogiannaki, P. Prassopoulos, N. Gourtsoyiannis


58 years, female

No Area of Interest ; Imaging Technique CT
Clinical History
A 58 year old female admitted for cholecystectomy. Preoperative chest radiograph was abnormal but no respiratory complaints were referred.
Imaging Findings
A 58 year old female was admitted for cholecystectomy. The preoperative chest radiograph showed diffuse parenchymal opacification in both middle and lower lung fields and discrete deposits of calcific density at the periphery of lung bases. A zone of increased lucency between the lung parenchyma and the ribs was observed (FIG 1). The patient denied any respiratory symptoms. Pulmonary function tests revealed a mild restrictive defect with reduced total lung capacity. A chest HRCT revealed confluent calcific densities throughout all lung fields, more prominent in the middle and lower ones (FIG 2a, 2b). Discrete calcified micronodules were depicted subpleurally in the less involved upper lung fields as well as multiple, tiny subpleural cysts with a ribbon-like appearance. (FIG 2c).
Pulmonary alveolar microlithiasis is a rare disease characterized by the presence of innumerable tiny calculi, composed of calcium phosphate, within alveolar air-spaces. The aetiology and pathogenesis are unknown. A familial occurrence has been noted in approximately half of the reported cases. The severity of the x-ray imaging is not usually associated with the patients clinical condition which may be without symptoms (1). The radiographic pattern consists of very fine micronodulation involving both lungs, more severe over the lower than the upper zones. Although the opacities often coalesce and a normally exposed chest radiograph shows the lungs uniformly white, individual deposits are usually identifiable. A zone of increased lucency between the lung and the ribs known as "black pleura line" has been attributed to subpleural emphysema or a fatty layer in HRCT studies (1,2,3). HRCT also reveals high concentration of microliths in the subpleural parenchyma and along bronchovascular bundles (4). The diagnosis of pulmonary alveolar microlithiasis usually can be made with confidence from the classic radiographic pattern and the striking radiological-clinical dissociation. Microliths can be identified in sputum, bronchoalveolar lavage fluid, and transbronchial biopsy specimens (1).
Differential Diagnosis List
Pulmonary alveolar microlithiasis
Final Diagnosis
Pulmonary alveolar microlithiasis
Case information
DOI: 10.1594/EURORAD/CASE.740
ISSN: 1563-4086