Two case reports of ovarian clear cell carcinoma: Atypical MRI findings with a renal corticomedullary contrast-like appearance

The MR images of the two cases of ovarian clear cell carcinomas (CCCs), presenting as entirely solid-masses, revealed a band-like peripheral area and a geographic central area: The peripheral area images resembled those of the renal cortex, while the central area images resembled those of the renal medulla. Compared to the iliac muscle, the band-like peripheral area appeared iso-hyperintense on T2-weighted imaging (T2WI), isointense on unenhanced T1-weighted imaging (T1WI), hyperintense on diffusion-weighted imaging (DWI), and hypo-isointense on an apparent diffusion coefficient (ADC) map, with gradual enhancement on dynamic contrast-enhanced T1WI. The geographic central area of the tumor appeared hyperintense on T2WI, hypointense on T1WI, hypointense on DWI, and hyperintense on an ADC map, with less enhancement on dynamic contrast-enhanced T1WI. Simple total hysterectomy, salpingo-oophorectomy, and partial omentectomy were performed in both cases. Both tumors were entirely solid, and histopathological analysis revealed cancer cell proliferation accompanied by an increase in stromal fibrous tissue in the peripheral area. Edematous stroma and fibrosis were predominantly observed with minimal cancer cells in the central area. The patients were diagnosed with ovarian CCC (pT1a). The mechanism behind the appearance of peripheral and central areas with renal corticomedullary contrast in such cases remains unknown, and MRI can provide valuable insights for the differential diagnosis of epithelial ovarian cancer.