Alveolar microlithiasis appears in Chest X-ray as diffuse, very fine micronodules of calcific density that are usually asymptomatic. Characteristic black pleura sign (it is due to contrast between the extreme density of the lung parenchyma on one side of the pleura and the ribs on the other side).
Alveolar microlithiasis. Nearly uniform distribution of typical fine, sandlike mottling in the lungs. The tangential shadow of the pleura is displayed along the lateral wall of the chest as a dark lucent strip (arrows).