THU189 Complex Treatment Of Recurrent Gynecomastia In An Affirmed Male With 46XX Ovotesticular Difference Of Sexual Differentiation (DSD).

Disclosure: S. Jumani: None. K. Shimy: None. D. Casella: None. J. Long: None. V. Gomez-Lobo: None. Introduction: Identifying gonads with ovarian and testicular components (ovotestis) can be difficult, despite multimodal imaging, biopsy, and surgical visualization. Here, we describe an unexpected identification of an ovotestis following the initiation of tamoxifen in a patient with 46XX Ovotesticular Difference of Sexual Differentiation (DSD). Case: A 14YO affirmed male with 46XX Ovotesticular DSD presented to our clinic for management of recurrent gynecomastia. At birth, he had ambiguous genitalia consistent with a under-virilized phallus, dorsally hooded foreskin, bifid scrotum, proximal hypospadias, palpable left gonad and non-palpable right gonad. He had a “normal” testosterone (i.e. presumably in male range for mini-puberty, though specific values predate available records). Limited genetic testing showed a karyotype of 46XX and negative SRY. He underwent a laparoscopy during which a right ovary, Müllerian tissue, and a small amount of vaginal tissue were identified and removed. A biopsy of the left gonad showed Sertoli cells without germinal epithelium. In adolescence, he developed progressive gynecomastia, with tanner 3 breasts by 12y6m. Treatment with anastrozole was unsuccessful, and he underwent a reduction mammaplasty at 13y6m. Unfortunately, the gynecomastia recurred shortly thereafter, and he was referred to our institution. At 14y7m bloodwork revealed a robust testosterone (543ng/dL), elevated estradiol (106 pg/mL, ref: 10-36), and estrone (71pg/mL, ref: 15-45). A trial of 20 mg tamoxifen daily was initiated. After 1 month, he developed scrotal pain suspicious for torsion and was taken to the operating room. Scrotal exploration revealed a hemorrhagic cyst at the superior pole of the gonad and an external appearance consistent with an ovo-testis. The hemorrhagic cyst was drained, and the remainder of the gonad left in situ. His pain resolved post-operatively however he returned 3 weeks later with scrotal pain and a recurrent hemorrhagic cyst on ultrasound. Tamoxifen was discontinued, and treatment with a Gonadotropin Releasing Hormone agonist (GnRHa) and concomitant testosterone replacement was initiated. This medication change led to resolution of the gonadal cysts. Conclusion: Initiation of tamoxifen as treatment for gynecomastia resulted in recurrent hemorrhagic cysts and the identification of ovarian tissue in a descended gonad which was presumed to be a biopsy proven testis. Recurrent hemorrhagic cysts in the ovotestis were likely due to physiologic stimulation and tamoxifen(1) as well as elevated estradiol. Treatment with a GnRHa and testosterone offered a reversible, non-surgical method to suppress endogenous sex hormones contributing to gynecomastia while continuing male pubertal development. 1.PMID: 16254040. Presentation: Thursday, June 15, 2023