The diagnostic accuracy of a solitary pulmonary nodule, using thin-section high resolution CT: a solitary pulmonary nodule by HRCT.

A solitary pulmonary nodule (SPN) less than 2 cm in diameter of 60 patients was evaluated with thin-section, high-resolution computed tomography (HRCT). The presence of an irregular margin, speculation, convergence of the surrounding structure, an air bronchogram and the involvement of more than 3 vessels was observed more frequently in malignant nodules than in benign nodules. When one point was given for each finding, the mean total scores of each histologic type were as follows; adenocarcinoma; 2.7, squamous cell carcinoma; 2.5, benign tumor; 0.3, tuberculosis; 1.3, pneumonia; 2.0. When SPNs were classified by the total scores, the SPNs with higher scores (> or = 3) included 18 of 33 (56%) malignant lesions and only 2 of 28 (7%) benign lesions. This means that sensitivity and specificity in the diagnosis of malignancy in the SPNs with high scores were 56% and 93%, respectively. These observations suggest that SPNs with a score higher than 3 points would be highly suspicious for malignancy but the number of such SPNs is rather limited. Therefore, more sophisticated methods may be necessary to better differentiate between malignant and benign SPNs.