Normal pelvic ultrasound or MRI does not rule out neoplasm in patients with gonadal dysgenesis and Y chromosome material.

INTRODUCTION: Patients with gonadal dysgenesis (GD) with a Y chromosome have an increased risk of gonadal neoplasm. Few data exist on the ability of imaging to detect malignancy in intra-abdominal gonads in these patients.

OBJECTIVE: We aimed to determine the correlation between preoperative imaging findings and gonadal pathology in GD patients with Y chromosome material.

METHODS: A retrospective review was performed of patients with XY or XO/XY GD who underwent gonadectomy at our institution from 2003 to 2017. Patients were assessed preoperatively with ultrasonography; some additionally underwent MRI.

RESULTS: The series consisted of 10 patients, all with female gender and non-palpable gonads. Median age was 13.1 years (range 2.4-18.3 years). Overall, four of the ten patients (40%) had a tumor (gonadoblastoma or dysgerminoma) on final pathology. Four patients had a gonad or gonads that were definitively seen on ultrasonography. All visualized gonads were described as "normal" or "small" with the exception of one patient, who had a normal MRI. Three of the four patients in this group had a tumor on final pathology. The remaining six patients had a gonad or gonads that were not definitively visualized on ultrasound; one patient in this group had a tumor on final pathology. Overall, five of seven gonads (71%) definitively visualized on ultrasound had tumor on final pathology, and two of thirteen gonads (15%) not visualized on ultrasound had tumor on final pathology; this difference was statistically significant (p = 0.012). Three patients were imaged with MRI. Of the gonads that could be visualized on MRI, no definitive abnormalities were seen. All patients imaged with MRI had tumors on final pathology.

DISCUSSION: Both ultrasound and MRI are relatively poor at identifying and characterizing intra-abdominal gonads in GD patients. The majority of patients who had a neoplasm had normal imaging findings. Gonads that were definitively visualized on ultrasound were more likely to contain neoplasms that could not be visualized, which perhaps because of tumor growth. No other consistent imaging findings of malignancy were found. Our study included ultrasound evaluations that were completed over 10 years ago and not performed by pediatric ultrasonographers, which may have biased the results. However, results suggest that when discussing gonadectomy with GD patients, one should not be reassured by "normal" imaging findings. Neither ultrasound nor MRI should be relied on for surveillance in GD patients who decide against gonadectomy.

CONCLUSION: A normal ultrasound or MRI does not rule out neoplasm in GD patients with intra-abdominal gonads.