OR05-1 Testicular Magnetic Resonance Imaging (MRI) Findings and Predictive Factors of Gonadal Neoplasia in Complete Androgen Insensitivity Syndrome

INTRODUCTION: Complete Androgen Insensitivity Syndrome (CAIS) is characterized by a complete external genitalia appearance and testicular development in 46,XY individuals carrying inactivating mutations in the AR gene. Prophylactic gonadectomy versus saving gonads has been debatable in CAIS management, mainly due to the absence of an accurate biomarker for testicular germ cell tumors (GCT). OBJECTIVE: to cross the preoperative pelvic MRI data with the histological gonadal findings from CAIS patients who underwent prophylactic gonadectomy to identify predictive factors of GCT development. METHODS: We evaluated 30 gonads from 15 CAIS patients with proven AR mutation. All performed pelvic MRI before gonadectomy through the same MRI machine and were included in the MRI data analysis. Three blinded radiologists specialized in urology performed image analysis. The immunohistochemical markers PLAP, c-KIT, OCT3/4, SALL4, ER, alpha-inhibin, CD99, and calretinin were performed. RESULTS: Nine (60%) performed gonadectomy after puberty (>16 years old). We identified one case of classical seminoma and one case of Sertoli cell neoplasia (at 18 and 19 years of age, respectively). Overall, the prevalence of neoplasia was 13.3%. No case of premalignant intratubular germ cell neoplasia was detected.Histological data revealed a high prevalence of benign lesions (n=12; 80%). Leydig Cell Hyperplasia (67%), stromal fibrosis (53%), Sertoli Cell nodules (47%), hamartomatoums nodules (40%) and paratesticular cysts (67%) which are more frequent after puberty (p<.01). MRI detected heterogeneity in all cases harboring hamartomatoums nodules, Sertoli cell nodules, and testicular neoplasia. Benign lesions were bilateral in all cases. Regarding the MRI data, the presence of testicular cystic mass (by tumoral necrosis) on MRI and tumor size (higher among malignancies) correlated with malignancy (p=.008 and p=.03, respectively), whereas gonadal location (inguinal/abdominal), presence of solid nodules, T2WI and postcontrast features, nodule diffusion restriction, and presence of perigonadal cysts did not. Chronological age >16 years was associated with malignancy with a 4.3 OR (1.6–11.69). CONCLUSION: Pelvic MRI is sensitive to detect gonadal nodules in CAIS patients, regardless of the gonad position, but most nodules are benign. Testicular malignancy should be suspicious in the presence of testicular cystic mass and large testis size in CAIS patients >16 years old. Presentation: Saturday, June 11, 2022 11:30 a.m. - 11:45 a.m.