Ovotesticular cords and ovotesticular follicles: New histologic markers for human ovotesticular syndrome.

Introduction: The presence of an ovotestis is a rare difference of sex development. The diagnosis can be difficult with the gold standard being the presence of both testicular cords and ovarian follicles within the same gonad.

Objective: Herein we describe two new markers of ovotesticular syndrome: ovotesticular cords and ovotesticular follicles.

Study Design: Twenty human gonads with a previous diagnosis of ovotestis were re-stained with markers for testicular cords (SOX9, TSPY, SALL4, DDX4, cP450, AR, α-actin) and ovarian tissue (FOXL2, SALL4, DDX4). Ovotesticular cords were defined as structures expressing both testicular Sertoli cell marker (SOX9) and an ovarian follicular cell marker (FOXL2), and in Y chromosome positive specimens, TSPY-positive testicular germ cells. Ovotesticular follicles were defined as a hybrid ovarian follicle containing FOXL2-positive granulosa cells and a central oocyte, but also containing cells expressing the testicular Sertoli cell marker, SOX9, intermingled within FOXL2-positive granulosa cells and male and female germ cells.

Results: Six of twenty ovotestis did not meet our criterion for the diagnosis of ovotestis lacking the histologic evidence of both testicular and ovarian tissue. The remaining 13 patients in which 14 separate specimens were evaluated, contained ovotestis defined by the presence of testicular cords and ovarian follicles. Eleven of the 14 ovotestis specimens (79 %) contained ovotesticular cords. Four of 11 ovotestis specimens (36 %) contained ovotesticular follicles.

Discussion: We recommend using eight immunohistochemical markers to diagnose an ovotestis: 1) SOX9, TSPY, SALL4, DDX4, cytochrome P450, AR, smooth muscle α-actin for the testicular component and FOXL2 and SALL4, DDX4 for the ovarian component. SOX9 and TSPY (useful only in the presence of a Y karyotype) are specific testicular markers and FOXL2 the only specific ovarian marker. We found ovotesticular cords and ovotesticular follicles in both human bipolar and mixed ovotestis specimens both with and without the presence of the Y chromosome. The clinical significance of ovotesticular cords and follicles remains unknown. We did not observe any obvious abnormalities in cellular architecture with the juxtaposition of testicular cells and ovarian cells.

Conclusion: We have identified two new structures in humans with ovotestis, ovotesticular cords and ovotesticular follicles (Figure), which appears to be additional markers to facilitate the diagnosis of ovotesticular gonads.