Two case reports of ovarian clear cell carcinoma with central necrosis representing a mille-feuille-like appearance on contrast-enhanced MRI

Magnetic resonance imaging (MRI) findings in two cases of ovarian clear cell carcinoma (CCC) revealed solid masses with extensive central necrosis. At the interface between the necrotic and viable solid components in the central portion of the tumors, contrast-enhanced T1-weighted images showed a striped or finely layered appearance suggestive of a mille-feuille - like appearance. Histologically, this appearance corresponds to alternating layers of tumor cells and necrotic or fibrotic tissues. The solid component, predominantly located at the periphery of the tumor, showed mild hyperintensity on T2-weighted imaging (T2WI) with multiple linear hypointense streaks and isointensity on unenhanced T1-weighted imaging (T1WI), with gradual enhancement on dynamic contrast-enhanced T1WI relative to the myometrium. It displayed hyperintensity on diffusion-weighted imaging (DWI) and hypo- to isointensity on the apparent diffusion coefficient (ADC) map. The necrotic component occupying the central portion of the tumor appeared hypointense on DWI and hypo- to hyperintense on the ADC map. It showed heterogeneous hyperintensity on T2WI, and hypoisointensity on T1WI, without enhancement on dynamic contrast-enhanced T1WI. Simple total hysterectomy, bilateral salpingo-oophorectomy, partial omentectomy, and pelvic lymph node dissection were performed in both cases. Both tumors appeared as solid masses with central necrotic and fibrotic areas. Histopathological examination confirmed CCC, and the final diagnosis was ovarian CCC classified as pT1a and pT1c3. The mechanism underlying the mille-feuille - like appearance in these cases remains unclear; however, this MRI finding may provide valuable insights into the differential diagnosis of epithelial ovarian cancers.