Study of the relationship between world health organization histological classification of thymic epithelial tumors and CT features

Objective: To investigate the CT findings of thymic epithelial tumors (TETs). Methods: The CT images of 133 cases with TETs confirmed pathologically were reviewed retrospectively. The TETs were reclassified according to WHO 2004 Classification System. The CT features of different histopathological types of TETs were analyzed. The frequencies of demonstrating these CT features were compared between different types using Chi-square exact test. Results: Type A (9/10, 90.0%), AB (15/17, 88.2%), Bl (10/13, 76.9%), and B2 (31/46, 67.4%) tumors were more likely to have spherical or oval shapes and smooth contours on CT. TETs with irregular or lobular contours were mostly seen in type B3 (21/30, 70.0%) and thymic carcinoma (15/17, 88.2%). TETs with cyst and necrosis formation were common in type A (6/10, 60%), B3 (19/30, 63.3%) and thymic carcinoma (15/17, 88.2%). Calcification was more frequently seen in type B2 and B3 (32/76, 42.1%) than any other type of TETs (8/57, 14.0%; χ2= 12.20, P<0.01). Type A, AB, B3 and thymic carcinoma had higher prevalence of significant enhancement (39/74, 52.7%) than type B1 and B2 (8/57, 13.6%; χ2=22.01, P<0.01). Conclusion: According to WHO 2004 histologic classification system, different types of TET have corresponding CT features. CT has showed the potentiality in differentiating histological subtypes of TETs. (authors)