(6) A supernumerary ovary in an adolescent

Background: Supernumerary ovaries are a rare gynecologic condition in which ovarian tissue develops separate from the normally placed ovaries without ligamentous connection to other reproductive structures. These ovaries are hypothesized to arise from a separate primordium, rather than as sequelae of a surgical or inflammatory process. We present a unique case of a suspected supernumerary ovary arising directly from the aorta in an adolescent, which supports the ‘arrested oocyte migration’ theory.

Case: A 16-year-old female presented with two years of worsening right lower quadrant pelvic pain. Pelvic ultrasound identified a peripherally calcified structure in the right adnexa measuring 2 cm with normal uterus and bilateral ovaries. Perplexingly, the mass appeared to have shifted to the left pelvic cul-de-sac upon pelvic MRI, which further characterized the mass as well-circumscribed, calcified, and distinct from the ovaries. No Müllerian or urologic abnormalities were identified.

A subsequent diagnostic laparoscopy identified a 3 cm mass that very strongly resembled a third ovary, and a normal uterus, tubes, and ovaries. This mass was attached to a thin, 8 cm stalk arising directly from the aorta and was freely mobile in the pelvis without connections to other reproductive structures. Clinically, this appeared consistent with a chronically torsed, supernumerary ovary. The mass was excised at the stalk approximately 2 cm above its origin at the aorta and sent for pathologic examination. The procedure was uncomplicated, and the patient was discharged home the same day in stable condition. Pathology revealed a benign appearing cystic mass surrounding necrotic tissue with focal dystrophic calcification. The nature or origin of this cystic mass was uncertain given the extensive necrotic nature of the specimen. Nevertheless, the mass’s clinical presentation and distinct appearance intraoperatively is indicative of a supernumerary ovary.

Comments: The present case describes a suspected supernumerary ovary with features analogous to normal ovarian embryology including attachment directly from the aorta (potentially prior blood supply) and evidence of pelvic descent. These findings shed light on the complex embryologic origins of the reproductive system and support the hypothesis that supernumerary ovaries arise from the arrest of oocytes during their migration to the genital ridge, with subsequent differentiation of surrounding mesenchyme into ovarian tissue. It is important for providers to be aware of this diagnosis given its association with other genitourinary anomalies (e.g. Müllerian agenesis) and variable presentation including pain, abnormal bleeding, torsion, or malignancy/neoplasm.