Ultrasmall pulmonary opacities on multidetector-row high-resolution computed tomography - A prospective radiologic-pathologic examination

Objective: To clarify the pathologic findings of ultrasmall pulmonary opacities (5 mm or smaller in diameter) found on multidetector-row high-resolution computed tomography (MD-HRCT). Methods: Ten lobes in 10 patients were included in this study. Each lobe had a primary lung tumor and was removed surgically. Two thoracic radiologists noted any tiny nonlinear opacity on preoperative MD-HRCT films (1.25-mm thickness) covering the whole lobe. Pathologic findings of detected opacities were evaluated macroscopically and microscopically. Results: Among 139 ultrasmall opacities 5 mm or smaller in diameter, 94 corresponded to normal anatomic structures (partial volume averaging or motion artifact), 36 corresponded to pathologic abnormalities, and 9 were unidentified. Histologic diagnoses of 36 pathologic abnormalities were inflammatory lesions (n = 16), intrapulmonary lymph nodes (IPLN; n = 7), atypical adenomatous hyperplasia (AAH; n = 7), bronchioloalveolar carcinoma (BAC; n = 5), and another neoplastic lesion (n = 1). Conclusion: Tiny pulmonary lesions, such as AAHs, BACs, and IPLNs, were identified among ultrasmall opacities found on MD-HRCT.