Virilizing ovarian hilus (Leydig) cell tumor with concurrent contralateral hilus cell hyperplasia: a rare diagnosis.

Ovarian hilus or Leydig cell tumor and ovarian hilus cell hyperplasia are rare clinical entities, causing virilization in both pre- and postmenopausal women. Differentiation between these two conditions is not always straightforward; the former is usually unilateral appearing as a single, grossly visible, circumscribed mass of hilus cells, while the latter is usually bilateral, appearing as diffuse microscopic aggregates of hilus cells. We report herein an extremely rare case of ovarian hilus or Leydig cell tumor, presenting concurrently with contralateral ovarian hilus cell hyperplasia in a postmenopausal woman with virilization. To the best of our knowledge, only four such cases have been previously reported in the literature. Ovarian hilus cell tumors and hilus hyperplasia almost always have benign biological behavior, thus making bilateral salpingo-oophorectomy an appropriate and sufficient therapeutic approach.