Pulmonary calcinosis.

The clinical and pathological features are described of a case of pulmonary calcinosis complicating cystic disease of the renal medulla. A histopathological study of the lung revealed calcification in the alveolar walls and in the blood vessels, predominantly in the pulmonary veins and venules. The calcified deposits were also studied by electron microscopy, and appearances suggestive of active growth of the deposits were recognised. Chemical analysis of the lung revealed a calcium content some 55 times greater than that of a normal lung. There was a five-fold increase in magnesium content. Reference is made to the literature demonstrating that the chemical composition of metastic calcification differs according to whether it is visceral or non-visceral in type.