A Case Report: Ovarian Fibrothecoma with Minor Sex Cord Elements

Ovarian stromal tumors with minor sex cord elements are rare, and there are not specific imaging features to help in making the diagnosis.

We report a case of this tumor in an 81-year-old woman who was referred to our hospital for constipation and a pelvic mass. Magnetic resonance imaging demonstrated a well-circumscribed mass and isointensity compared to the skeletal muscle on T1-weighted imaging (T1WI) and low signal intensity mixed with high signal ranges on T2-weighted imaging. Dynamic gadolinium-enhanced fat-suppressed T1WI revealed mild and increased enhancement of the peripheral area in the early and delayed phases, respectively. On diffusion-weighted imaging (DWI), a heterogeneously high signal intensity corresponding to the peripheral enhanced area was observed, and the apparent diffusion coefficient values of the high-intensity areas on DWI were low. Malignancy could be suspected, so the mass was surgically removed. Pathological assessment revealed a fibrothecoma with minor sex cord elements.

The tumor's preoperative diagnosis is difficult, although the possibility of this rare tumor from atypical findings on DWI and/or dynamic contrast enhancement studies should be considered.