Pulmonary alveolar microlithiasis: CT findings.

We present five cases with confirmed diagnosis of pulmonary alveolar microlithiasis that illustrate the appearance of this rare chronic lung disease on conventional and high-resolution CT. Pulmonary alveolar microlithiasis is characterized by widespread intraalveolar calcification of both lungs. Conventional CT confirmed the inferior and posterior predominance of the lesions in four of our cases and showed an exceptionally high concentration of microliths in the subpleural parenchyma and along the bronchovascular bundles. High-resolution CT revealed a perilobular and bronchovascular distribution of the disease process at the level of the secondary pulmonary lobule. This pattern correlated closely with pathologic findings.