http://radiographics.rsna.org/content/24/2/387.full

Teruko Ueno, MD ; Yumiko Oishi Tanaka, MD ; Michio Nagata, MD ; Hajime Tsunoda, MD ; Izumi Anno, MD ; Shigemi Ishikawa, MD ; Koji Kawai, MD ; Yuji Itai, MD†

¹ From the Department of Radiology, Tsukuba University Hospital, 2-1-1 Amakubo, Tsukuba, Ibaraki 305-8576, Japan (T.U.); and the Departments of Radiology (Y.O.T., I.A., Y.I.), Pathology (M.N.), Obstetrics and Gynecology (H.T.), Thoracic Surgery (S.I.), and Urology (K.K.), University of Tsukuba, Ibaraki, Japan. Presented as an education exhibit at the 2002 RSNA scientific assembly. Received March 27, 2003; revision requested May 30 and received August 18; accepted August 20. All authors have no financial relationships to disclose.

Germ cell tumors (GCTs) occur most frequently in the gonads and are relatively rare in other sites, such as the pineal gland, neurohypophysis, mediastinum, and retroperitoneum. GCTs are thought to originate from primordial germ cells, which migrate to the primitive gonadal glands in the urogenital ridge. Extragonadal GCTs might also originate from these cells when the cells are sequestered during their migration. Pathologic subtypes of GCTs vary, and the prevalence of mixed tumors is high. These factors produce a diversity of radiologic findings and make prospective radiologic diagnosis difficult in many cases. However, similar radiologic findings have been observed in pathologically equivalent tumors in varying sites. Seminomas appear as uniformly solid, lobulated masses with fibrovascular septa that enhance intensely. Nonseminomatous GCTs appear as heterogeneous masses with areas of necrosis, hemorrhage, or cystic degeneration. Fat and calcifications are hallmarks of teratomas, most of which are benign. In immature teratomas, scattered fat and calcification within larger solid components are occasionally seen. These imaging characteristics reflect the pathologic features of each tumor, and histologically similar GCTs at varying sites have similar radiologic features. Knowledge of the pathologic appearances of GCTs and their corresponding radiologic appearances will allow radiologists to diagnose these tumors correctly.