Abstract:Objective: To develop the diagnostic level of bronchioloalveolar carcinoma(BAC) by analyzing the clinical features and CT presentations of BAC. Materials and Methods: All the cases of BAC comfirmed by operation and pathology were retrospectively analyzed from June 2002 to June 2007. These cases were review using the 2004 revised WHO classification of BAC and separated them into two groups, pure BAC and mixed subtype adenocarcinoma with BAC components. The CT presentations of pure BAC were analyzed. Evaluated findings included the number(solitary or multiple), size, morphous, contours, density and gas-containing space of lesions. Other CT findings such as air bronchogram, vascular converging and lymphadenopathy were also assessed. Results: 145 surgically resected cases with thin-section CT images were histologically diagnosed as BAC from 2002 to 2007. Of these, 32(22.1%) proved to be pure BAC using the 2004 revised WHO classification. There were 20 men(62.5%) and 12 women(37.5%). The positive rate of tumor markers CEA and CA125 was 10% and 5%, respectively. The mean diameter of BAC was less than 3cm and all of the cases presented pure ground glass opacity. 82.9% of them showed inhomogeneous density, 97.1% well-defined margin. The rate of lobulated shape, air bronchogram and gas-containing space were 62.9%, 60%, 57.1%, respectively and lymphadenopathy in none of these BAC. Conclusion: In the diagnosis of early stage of BAC, some morphologic features of lesions on thin slice CT may be more important.