Teratomas are most commonly observed as lesions of ovarian origin. They can also be detected
in extragonadal regions such as brain, face, neck, mediastinum, retroperitoneum, and sacrococcygeal
region. Ovarian teratomas are usually in mature cystic form as benign, well-differentiated, and
cystic lesions. Immature teratomas and monodermal teratomas (struma ovarii, carcinoid tumors and
neural tumors) are rare forms. Mature cystic teratomas are usually diagnosed by ultrasound (US) and
magnetic resonance (MR) imaging. On US, a variety of appearances including echogenic sebaceous material and calcification
are observed. MR imaging can specifically demonstrate fat component by fat-saturation sequences. On the other
hand, teratomas are usually incidentally detected on computed tomography (CT) and fat attenuation within a cyst is diagnostic.
It may be difficult to characterize immature teratomas due to nonspesicific findings on US. However, CT and MR
can provide diagnosis by identifying small foci of fat within a mass with irregular solid component containing coarse calcifications.
A small proportion of mature cystic teratomas can undergo malignant transformation (carcinomas or sarcomas).
The purpose of this paper is to review the imaging features of various types of abdominally located teratomas for
differentiation and diagnosis.