Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Metastatic Calcification
- Radiologic Findings
- Figs 1-4. Multifocal ill-defined nodular ground glass opacity lesions are shown in both lungs on axial images of chest CT.
Fig 5. Multifocal ill-defined nodular ground glass opacity lesions show slight upper lung predominancy on coronal image of chest CT.
Figure 6. On Tc-99m MDP bone scan images, diffuse uptake is seen in both lungs.
Patient had a history of glomerulonephritis when he was 12 years-old. He has been undergoing hemodialysis since 16 years ago. Patient showed hypercalcemia and was diagnosed as secondary hyperparathyroidism due to end stage renal disease. He underwent surgery for calcinosis cutis on the scrotum, may be also related to secondary hyperparathyroidism.
- Brief Review
- Metastatic calcification refers to the deposition of calcium in soft tissue due to abnormal calcium and phosphate metabolism. It is associated with hypercalcemia and is most common in patients with chronic renal failure and secondary hyperparathyroidism. It is reported to be present in 60-80% of patient with chronic renal failure at autopsy. Pathologically, metastatic pulmonary calcification is an interstitial process and depositions are seen predominantly in the alveolar septa, pulmonary arterioles and bronchioles.
Most patients with metastatic pulmonary calcifications are asymptomatic, but rarely in severe cases calcium depositions can lead to interstitial fibrosis, restrictive lung function and result in respiratory insufficiency.
Calcium salts precipitate in alkaline environment. Due to increased ventilation-perfusion ratio in lung apex compared to base, lung apex demonstrate lower PaCO2 and higher blood pH. It is hypothesized that because of this difference of pH between apex and base, metastatic calcification has a greated propensity to occur in upper lobes.
Plain radiographs are relatively insensitive in detecting metastatic calcification. In some patients, ill-defined nodules, or patchy areas of increased opacity may be seen. CT can show areas of ground glass opacity, consolidation, or calcification. Numerous fluffy and poorly defined nodules, measuring 3 to 10 mm in diameter, are typical, but opacities can appear focal, lobular, patchy, or diffuse. Even with HRCT, these opacities may not appear calcified. An apical predominance is common, because the apices are more alkaline than the bases, increasing the likelihood of calcium salt precipitation in this region.
Tc-99m MDP bone scintigraphy shows increased uptake in both lungs. Tc-99m MDP bone scintigraphy or mediastinal images on HRCT scan may be diagnostic of metastatic calcification without need for further investigation.
- References
- 1. Marchiori E, Muller NL, Souza AS Jr, et al. Unusual manifestations of metastatic pulmonary calcification: high-resolution CT and pathological findings. J Thorac Imaging. 2005;20:66-70.
2. Chan ED, Morales DV, Welsh CH, et al. Calcium deposition with or without bone formation in the lung. Am J Respir Crit Care Med. 2002;165:1654-1669.
3. Elem LC, Zanetti G, Souza AS Jr, et al. Metastatic pulmonary calcification: State-of-the-art review focused on imaging findings. Respir Med. 2014 May;108(5):668-76.
- Please refer to
- Case 716 Case 628 Case 450 Case 169
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- Keywords
- Lung, Lung, Metabolic pulmonary disease,