CT FINDINGS IN MALIGNANT-TUMORS OF THYMIC EPITHELIUM

Objective: Differentiation of invasive thymoma from thymic carcinoma i s important because of their different clinical behaviors. Retrospecti vely, we evaluated the CT findings of invasive thymomas and thymic car cinomas to determine the differential points between them. Materials a nd Methods: We reviewed the CT scans of 12 patients with invasive thym oma and 10 patients with thymic carcinoma that were confirmed by surge ry or percutaneous needle aspiration. We analyzed CT scans, paying spe cial attention to homogeneity, attenuation, invasion of adjacent media stinal structures, pleural implants, mediastinal nodes, and extramedia stinal metastases. Results: Most of the invasive thymomas and thymic c arcinomas were homogeneous and isodense with chest wall muscle. Irregu lar infiltration into the adjacent organ suggesting invasion was seen in 11 patients (92%) with invasive thymoma and 8 patients (80%) with t hymic carcinoma. Pleural implants were observed in four patients (33%) with invasive thymoma and one patient (10%) with thymic carcinoma. Me diastinal lymphadenopathy was seen in one patient (8%) with invasive t hymoma and four patients (40%) with thymic carcinoma. Metastases to th e lung, adrenal glands, or liver were observed in four patients (40%) with thymic carcinoma but none with invasive thymoma. Conclusion: Desp ite the similarities of CT findings between invasive thymoma and thymi c carcinoma, there are some differential points. Thymic carcinomas wer e infiltrating tumor and were more commonly associated with mediastina l nodes and extrathymic metastases, but less commonly associated with pleural implants than invasive thymoma.