Postoperative residual ovary syndrome: an uncommon cause of pelvic mass.

We report two patients with an ovarian mass following hysterectomy. These represent part of the spectrum of the "residual ovary syndrome." The retroperitoneal incarceration of a residual ovary and the presence of adhesions, preventing free access to the peritoneal cavity, result in an accumulation of follicular products locally and, thus, a mass with cystic and solid components. Differential diagnostic considerations include functional and dysfunctional ovaries, benign and malignant ovarian tumors, and endometriosis.