This pictorial review aims to help the viewer understand the following points in relation to rare germ cell tumours: Identify radiologic features that help characterize the lesion Consider the differential imaging diagnoses for each tumour and the follow up with other imaging modalities. Review the optimal MR protocol for evaluating adnexal lesions.

Malignant ovarian germ cell tumours are rare representing 5% of all ovarian malignant neoplasms. These tumours occur mostly in young women between the ages of 10 and 30 years of age1.The histologic types are similar to tumours developing in the male testes, with dysgerminoma, immature teratoma, yolk sac tumors, and mixed germ cell tumors accounting for 90 percent of cases and non-gestational choriocarcinomas being exceptional rare.2 Diagnosis is strongly suggested preoperatively by the presence of an adnexal mass on pelvic imaging and an elevated level...

Choriocarcinoma Epidemiology A rare highly aggressive malignant tumour with trophoblastic differentiation. Serum BHCG is elevated. Presentations include pelvic mass symptoms, amenorrhea, isosexual pseudo-precocity in prepubertal girls and bleeding from metastatic deposits.4 Two types: non-gestational occuring in prepubertal girls and postmenopausal women and gestational choriocarcinoma occuring during reproductive years requiring a recent intra/extrauterine pregnancy. Incidence of non-gestational choriocarcinoma is 2.1-3.4% of all OMGCT.5It metastases haematogously and via lymphatics. At presentation, often liver metastases and local pelvic invasion. Leading cause of death is brain metastases occurring in...

Germ cell tumours are rare with specific imaging characteristics.The aim of this pictorial review is to help the viewer characterise and identify these tumours.

E. Canniff; Dublin/IE - nothing to disclose M. Courtney; Dublin/IE - nothing to disclose S. Harte; Dublin/IE - nothing to disclose S. A. O'keeffe; Dublin/IE - nothing to disclose

References 1. Tewari K, Cappuccini F, Disaia PJ, Berman ML, Manetta A, Kohler MF. Malignant germ cell tumors of the ovary.Obstet Gynecol. 2000;95(1):128. 2. Gershenson DM.Ovarian germ cell tumors: Pathology, epidemiology, clinical manifestations, and diagnosis. September 2019. Uptodate.https://www-uptodate-com.(Accessed 11/10/2019) 3.ESUR Quick guide to female pelvis imaging.European Society of Urogenital Radiology.ESUR Female Pelvis Imaging Working Group April 2019. 4.Shaaban AM.Et al.Ovarian malignant germ cell tumors: cellular classification and clinical and imaging features.Radiographics.2014 May-Jun;34(3):777-801.5.Shaaban AM.Ovarian Choriocarcinoma. September 2019.Statdx.https://my.statdx.com. 6.Shaaban AM. Akin O.Dysgerminoma.https://my.statdx.com. (Accessed September 2019). 7.Imaoka I.et...