Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Metastatic Pulmonary Calcification
- Radiologic Findings
- Chest radiograph shows innumerable tiny nodular opacities in both lower lung zones. And Focal increased opacity is noted in left lower lobe.
Chest CT scan on lung window setting shows patchy area of ground-glass opacity in posterior basal segment of left lower lobe, suggestive of bronchopneumonia. It also demonstates multiple well-defined micronodules in right middle lobe and both lower lobes, which are revealed to be extensive dense calcifications on mediastinal window setting.
- Brief Review
- Most of the cases of metastatic pulmonary calcification occur in patients with hypercalcemia, particularly those with hyperparathyroidism secondary to chronic renal failure. Less common causes include hypercalcemia related to primary hyperparathyroidism, skeletal metastases, and multiple myeloma. Rarely, it may occur in patients with normal renal function, normal calcium and phosphate levels, and no underlying pulmonary disease.
Most of the patients with metastatic pulmonary calcification are asymptomatic and pulmonary function tests are usually normal. However, restrictive lung function, decreased diffusing capacity, hypoxemia, and, occasionally, respiratory failure may occur.
Metastatic calcification tends to involve mainly the upper lung zones. This distribution is presumed to be related to the higher ventilation-perfusion ratio in the upper lung zones as compared with the lower zones, which results in a lower partial pressure of carbon dioxide and thus a higher pH in the upper lung zones.
Metastatic pulmonary calcification is a process characterized histologically by the deposition of calcium salts predominantly in the interstitial tissue of alveolar septa with a particular affinity for elastic tissue. Other sites include walls of small blood vessels, bronchi, and bronchioles. Other sites include walls of small blood vessels, bronchi, bronchioles, and myocardium.
Chest radiograph is useful for detection of pleural calcification, hilar and mediastinal lymph node calcification, calcified lung nodules, diffuse parenchymal calcification. Diffuse calcification is often mistaken for another process such as pulmonary edema or intrapulmonary hemorrhage. Similarly, localized pulmonary calcification is often confused with infarction, pneumonia, or malignancy.
The HRCT findings include (1) multiple calcified and/or apparently noncalcified nodules distributed diffusely or more localized to the certain regions, (2) diffuse or patchy areas of ground glass opacification or ill-defined patchy infiltrate, and (3) a relatively dense area of consolidation. Moreover, calcification of the tracheobronchial walls and chest wall blood vessels may be seen. A ring pattern of nodular calcification was also described.
99mTC-MDP bone scintigraphy shows increased uptake in both lungs. 99mTC-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.
- Keywords
- Lung, Metabolic and storage lung disesae,