Figures 12, 13. (12) Left ovarian fibroma in a 41-year-old woman with pelvic pain and a palpable pelvic mass. Axial T2-weighted fast SE MR image shows a 5-cm-diameter adnexal mass with very low signal intensity (*) surrounded by attenuated ovarian stroma and follicles (arrows). The mass is separate from the uterus. Because MR imaging demonstrated that the mass was contained within the ovary, a diagnosis of leiomyoma of the broad ligament could be excluded. Histologic sections (not shown) revealed dense fibrous tissue admixed with foci of calcium. Ovarian fibromas contain focal or diffuse calcium in less than 10% of cases (43-45); along with fibrous tissue, calcium can result in low signal intensity on T2-weighted images. (13) Bilateral Brenner tumors and a left-sided serous cystadenoma with papillary projections in a 51-year-old woman. (a, b) Consecutive axial T2-weighted fast SE MR images (a obtained at a higher level than b) show bilateral adnexal masses (*) with lower signal intensity than an adjacent intramural-submucosal leiomyoma (curved arrow). There is an additional left adnexal mass with a thickened posterior wall and a small papillary projection along the anterior wall (straight arrow). The intraovarian location of this lesion and the difference in signal intensity between this lesion and the leiomyoma suggest a diagnosis of a fibrous adnexal neoplasm. Brenner tumors can be bilateral and are associated with other ovarian neoplasms in 30% of cases (42). (c) Photomicrograph (original magnification, x40; hematoxylin-eosin stain) of the solid left adnexal mass shows a focus of transitional cells (arrows) surrounded by reactive fibrous tissue. The nests of transitional cells are too small to be depicted as foci of intratumoral high signal intensity on T2-weighted images.