Idiopathic pulmonary ossification.

Idiopathic pulmonary ossification is an uncommon and asymptomatic disorder of unknown etiology in which trabeculated bone is found in the lung. It is usually mistaken for more serious entities radiographically, most commonly appearing as branching linear shadows of calcific density involving a limited area of the lung and exhibiting very slow progression; however, the shadows may be round or irregular and bulky. Sometimes the trabeculae are recognizable, and occasionally the lungs demonstrate widespread involvement. The authors describe 8 proven cases, including one in which a bone scan revealed uptake by heterotopic bone in the lung.