【Objective】To analyze computed tomography (CT) features of germ cell tumors of the mediastinum and to improve the diagnostic efficacy of CT for such tumor. 【Methods】 Forty patients with primary germ cell tumors of the mediastinum and proven pathologically were enrolled. All patients

including 24 patients with teratoma and 16 patients with non-teratomatous germ cell tumor

underwent non-enhanced and contrast-enhanced CT examinations. The CT features

including location

size

shape

edge

CT attenuation

involvement of adjacent structure and local or distant metastasis of each lesion were retrospectively analyzed.【Results】All the masses arose within the anterior mediastinum and their maximal diameter ranged from 5 cm to 16 cm (mean

11 cm). 24 masses of patients with teratoma appeared rounded or oval and well-circumscribed

20 of which revealed fat and calcification on non-enhanced CT images and showed light enhancement after contrast administration

the rest four masses revealed homogeneous water attenuation

and the capsule wall was thin and uniform with vaulted calcification on it. 11 and 5 masses of patients with non-teratomatous germ cell tumor appeared lobulated

ill-circumscribed and rounded or oval and well-circumscribed

respectively. 13 masses revealed heterogeneous attenuation on non-enhanced CT images with patchy low-attenuation foci whose attenuation is lightly larger than that of water and stippled calcification

and showed moderately heterogeneous enhancement after contrast administration. 3 masses of patients with seminoma revealed homogeneous attenuation and homogeneous enhancement after contrast administration. 6

6

10

and 3 cases of non-teratomatous germ cell tumor showed pericardial effusion

pleural effusion

involvement of adjacent vascular structures and pulmonary metastasis

respectively. 【Conclusions】The characteristic CT findings of mediastinal germ cell tumors reveal bulky masses in the anterior mediastinum. CT diagnosis for teratomas is easy because of the fat and calcification in the tumors. Most of non-teratomatous germ cell tumors show ill-circumscribed

lobulated masses

heterogeneous attenuation on non-enhanced CT images and heterogeneous enhancement after contrast administration. Seminomas may show homogeneous attenuation and homogeneous enhancement after contrast administration. The non-teratomatous germ cell tumor is apt to involve pericardium

pleura and adjacent vascular structure and develop distant metastasis. The differential diagnosis between non-teratomatous germ cell tumor and thymoma

lymphoma is needed.