Ovarian signet-ring stromal tumor: a potential diagnostic pitfall.

Signet-ring stromal tumor is a rare ovarian neoplasm with only 10 reported cases in the literature. We report an unusual case of ovarian signet-ring stromal tumor in a 69-year-old woman who presented with right adnexal mass and underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy. The diagnosis was based on histological, histochemical, immunohistochemical, and electron microscopy characteristics. The main significance is to differentiate this benign tumor from the highly malignant Krukenberg tumor, and this differential diagnosis is discussed.