[A case of ectopic pulmonary calcification appearing as diffuse ground-glass attenuation on HRCT]

A 50-year-old man was admitted to undergo an operation for aortic stenosis and insufficiency. Chest high-resolution CT (HRCT) showed diffuse areas with ground-glass attenuation in both lung fields. The shadows were not seen in the periseptal zones. A transbronchial lung biopsy specimen revealed ectopic interstitial calcification. Differential diagnosis upon observation of diffuse areas with ground-glass attenuation on HRCT included hypersensitivity pneumonitis and bronchopneumonia. In the peripheral region of the secondary pulmonary lobules, the microchemical environment of the alveoli tended to become alkalosed in comparison with the central area, the characteristic distribution of the areas of ground-glass attenuation may be explained by the differentiation of the acid-base balance between the peripheral and central regions of the secondary pulmonary lobules.