Temporal changes in magnetic resonance imaging appearance of adult granulosa cell tumor.

Granulosa cell tumors (GCTs) can have a wide variety of appearances on magnetic resonance imaging (MRI), ranging from entirely solid to multilocular cystic, suggesting that GCTs undergo remarkable morphological changes during growth. These temporal changes in MRI appearance of individual GCTs have not been documented. A 54-year-old asymptomatic postmenopausal woman was referred to our department for a small ovarian mass. This 3-cm solid mass showed high intensity on diffusion-weighted MRI and low intensity on apparent diffusion coefficient mapping. Close clinical follow-up was recommended, but she did not return to our hospital until the age of 63, when she was referred for a large ovarian tumor. MRI showed a 15-cm multilocular cyst containing a solid component with hemorrhaging. Postoperative diagnosis was adult GCT (AGCT). These temporal changes demonstrate a possible reason why GCTs can have such a wide range of MRI appearance. This knowledge might promote accurate preoperative diagnosis of AGCTs.