Calcium Deposition with or without Bone Formation in the Lung

Pulmonary calcification and ossification occurs with a number of systemic and pulmonary conditions. Specific symptoms are often lacking, but calcification may be a marker of disease severity and its chronicity. Pathophysiologic states predisposing to pulmonary calcification and ossification include hypercalcemia, a local alkaline environment, and previous lung injury. Factors such as enhanced alkaline phosphatase activity, active angiogenesis, and mitogenic effects of growth factors may also contribute. The clinical classification of pulmonary calcification includes both metastatic calcification, in which calcium deposits in previously normal lung or dystrophic calcification, which occurs in previously injured lung. Pulmonary ossification can be idiopathic or can result from a variety of underlying pulmonary, cardiac, or extracardiopulmonary disorders. The diagnosis of pulmonary calcification and ossification requires various imaging techniques, including chest radiography, computed tomographic scanning, and bone scintigraphy. Interpretation of the presence of and the specific pattern of calcification or ossification may obviate the need for invasive biopsy. In this review, specific conditions causing pulmonary calcification or ossification that may impact diagnostic and treatment decisions are highlighted. These include metastatic calcification caused by chronic renal failure and orthotopic liver transplantation, dystrophic calcification caused by granulomatous disorders, DNA viruses, parasitic infections, pulmonary amyloidosis, vascular calcification, the idiopathic disorder pulmonary alveolar microlithiasis, and various forms of pulmonary ossification.