CT demonstration of calcification in carcinoma of the lung

Radiologic visualization of calcification within lung cancer is uncommon and may cause confusion and misdiagnosis. For this reason, we reviewed CT records of 353 patients undergoing initial evaluation of lung cancer for the presence of calcification within the tumor, both to document this finding and to estimate its prevalence. Twenty patients (6%) whose records indicated that CT showed calcification were identified, and their chest radiographs and CT scans were analyzed. Patients were included in the study if calcium was seen within the tumor on noncontrast pretreatment CT scans and if pathologic data were available. There were 15 lung and five mediastinal tumors. Fourteen were 5 cm or greater in diameter; three were between 3 and 5 cm, and three were 2 cm or smaller. Cell types of the tumors included small-cell carcinoma (eight patients), squamous cell carcinoma (seven patients), adenocarcinoma (four patients), and undifferentiated carcinoma (one patient). Patterns of calcification were amorphous (eight patients), punctate (10 patients), and reticular (two patients). Extent of tumor calcification and distribution (central, peripheral, or diffuse) did not correlate with cell type or size of the lesion. The visualization of calcium on chest radiographs and CT scans does not alone exclude the diagnosis of bronchogenic carcinoma.