title: Associations between computed tomography features of thymomas and their pathological classification.
abstract: Background Thymoma exhibits a range of histological and biological features and their imaging findings varies. Purpose To evaluate the associations between CT findings of thymomas and their classification according to the Masaoka staging system and World Health Organization (WHO) classification. Material and Methods Eighty-four patients with thymoma were evaluated. Comparisons between the CT findings of Masaoka stage I/II and III/IV lesions, and the WHO type A-B1 (low risk) and B2/B3 (high risk) lesions were performed. Results Stage III/IV thymomas (mean size, 60 mm) were significantly larger than stage I/II (45 mm) lesions and had more irregular shape and contour. Necrosis and calcification were observed in 16 (59%) and nine (33%) stage III/IV thymomas, and 16 (28%) and seven (12%) stage I/II lesions, respectively. Regarding the WHO classification, the high-risk thymomas displayed irregular shape and contour more often than low-risk lesions. There were significant differences between the patterns of mediastinal invasion seen in high- and low-risk groups; 21 (68%) vs. six (12%) lesions demonstrated mediastinal fat invasion, seven (23%) vs. two (4%) lesions exhibited great vessel invasion, five (16%) vs. 0 (0%) lesions displayed pericardial invasion, and 18 (58%) vs. 10 (20%) lesions invaded the lungs, respectively. Conclusion Masaoka stage III/IV thymomas were larger in size, had more irregular shape and contour, and exhibited necrosis and calcification more often than the stage I/II lesions. In the WHO classification, high-risk thymomas demonstrated more irregular shape and contour than low-risk thymomas.
authors.affiliation: 1 Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ozawa
authors.affiliation: 2 Department of Radiology, Nagoya City West Medical Center, Nagoya, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Hara
authors.affiliation: 1 Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Shimohira
authors.affiliation: 1 Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Sakurai
authors.affiliation: 1 Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Motoo
authors.initials: M
authors.lastname: Nakagawa
authors.affiliation: 1 Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shibamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013945:Thymoma / Q000000981:diagnostic imaging* / Q000473:pathology*; D013953:Thymus Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
keywords: Masaoka stage; Thorax; computed tomography (CT); mediastinum; thymoma