This case demonstrates a large predominantly cystic mass in the pelvis of a young girl. Its fat tissue component and calcifications give the clue for the diagnosis of a mature cystic ovarian teratoma. It is really hard to consider another differential in this patient and with those radiologic features; a malignant degeneration is unlikely, however, it is impossible to exclude by imaging.

The diagnosis of this case is only based on images; no further clinical data were available.