Occurrence of Gonadoblastoma in Patients with 45,X/46,XY Mosaicism

Study Objective: To estimate the overall frequency of gonadal tumors in patients with 45,X/46,XY mosaicism who underwent gonadectomy and to determine whether the degree of external masculinization or the location of gonads were associated with the presence of gonadal tumor. Design: Retrospective study of patients with karyotype of 45,X/46,XY or variant who received care at the study institution between 1995 and2012. Setting: University of Michigan Health System (Ann Arbor, Michigan), a tertiary care academic center. Participants: Sixteen patients with karyotype of 45,X/46,XY who underwent gonadectomy. Interventions: None. Main Outcome Measure: Presence of pathology-confirmed gonadal tumor. Results: In patients who underwent bilateral gonadectomy, gonadoblastomas were detected in 36.4% (4 of 11), and all were identified in patients with normal female external genitalia (4 of 8 [50.0%]). Abdominal gonads were associated with a nonsignificant increase in rate of gonadal tumor compared with inguinal or scrotal gonads. No malignant tumors were identified. Conclusion: The overall rate of gonadoblastoma was higher than previously reported. The high rate of gonadoblastoma in patients with female external genitalia and the lack of gonadal function support continuing the standard of care of practice of prophylactic gonadectomy in this patient population.