Comparison of High-resolution CT Findings between Miliary Metastases and Miliary Tuberculosis

Purpose: To compare the findings of high-resolution computed tomography (HRCT) between patients with miliary metastases and miliary tuberculosis. Materials and Methods: Between May 1998 and April 2002, 11 patients with miliary metastases and 18 with miliary tuberculosis underwent HRCT, and we reviewed the findings. In miliary metastases, the primary lesions were adenocarcinoma of the lung (n=2), stomach (n=1), or pancreas (n=1), or of unknown origin (n=5), and papillary carcinoma of the thyroid (n=2). Two radiologists blinded to the clinical and pathologic data reached a consensus regarding nodule size and margin, their distribution and coalescence, interstitial involvement, and other ancillary HRCT findings. Data were analyzed using the chi-square test. Results: CT scans showed numerous 1 to 5-mm nodules randomly distributed throughout both lungs of all patients. Nodules larger than 1.5 mm in diameter were more often seen in miliary metastases (81.9%). In six (54.5%) patients with miliary metastases and in three (16.7%) with miliary tuberculosis, nodule size varied (p<0.05). Pleural effusion occurred in three (27.3%) patients with miliary metastases and three (16.7%) with miliary tuberculosis. Interlobular septal thickening (100%) and peribronchovascular thickening (63.6%) were more common in miliary metastases than in miliary tuberculosis (p<0.01). Lymph node enlargement was seen in 11 (100%) patients with miliary metastases and five (27.8%) with miliary tuberculosis (p<0.001). Conclusion: At HRCT, lymph node enlargement and both interlobular and peribronchovascular thickening are more commonly observed in miliary metastases than in miliary tuberculosis.