Invasive and noninvasive thymoma: Distinctive CT features

Purpose: The purpose of this work; was to evaluate the CT features of thymo ma and to determine the most helpful findings in differentiating invasive f rom noninvasive thymoma. Method: The CT scans from 27 patients with invasive thymoma and 23 with non invasive thymoma were independently assessed by two observers without knowl edge of their invasiveness. The presence and distribution of various CT fin dings were independently analyzed. Results: Invasive thymomas were more likely to have lobulated (16/27, 59%) or irregular (6/27, 22%) contours than noninvasive thymomas (8/23, 35% and 1.5/23, 6%, respectively) (p < 0.05). Invasive thymomas had a higher preval ence of low attenuation areas within the rumor (16/27, 60%) than noninvasiv e thymomas (5/23, 22%) (p < 0.001) as well as foci of calcification (14.5/2 7, 54% vs. 6/23, 26%; p < 0.01). Conclusion: The presence of lobulated or irregular contour, areas of low at tenuation, and multifocal calcification is suggestive of invasive thymoma.