Unusually intense ¹⁸F-fluorodeoxyglucose (FDG) uptake by a mature ovarian teratoma: a pitfall of FDG positron emission tomography.

We present a 32-year-old woman with an ovarian tumor. A large ovarian tumor with solid components was detected by ultrasonography and magnetic resonance imaging. Contrast enhanced magnetic resonance imaging showed strong enhancement within the solid component. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography was performed for further evaluation and intense FDG uptake into the solid component was observed with standardized uptake values of 12.8 in the early phase and 14.8 in the delayed phase. Therefore, we could not rule out the possibility of a malignant ovarian tumor, and the patient underwent unilateral salpingo-oophorectomy through laparotomy. The tumor was pathologically diagnosed as a mature teratoma with no malignant elements. Histological examination revealed the solid component to be composed mainly of central nervous tissue, which was most likely to be responsible for the intense FDG uptake.