A dynamic "hormonal tug-of-war" driven by a functioning ovarian remnant after testis-preserving partial gonadectomy in ovotesticular disorders of sex development: a case report.

The endocrine behavior of residual ovarian tissue following testis‑preserving surgery in ovotesticular disorders of sex development (DSD) during adolescence remains poorly characterized. We report an adolescent male who presented with Tanner stage B4 gynecomastia despite male‑typical external genitalia. Baseline evaluation revealed elevated gonadotropins, relative hyperestrogenism (estradiol 58.7 pg/mL), and SRY‑negative chromosome mosaicism (47,XX,+der(8)/46,XX). Pelvic imaging demonstrated a small prostate and bilateral intratesticular cysts, and laparoscopy and cystoscopy confirmed a male internal phenotype without Müllerian structures. Because firm intratesticular foci suggested the presence of ovarian tissue, testis‑preserving partial gonadectomy was performed. Histopathological examination revealed bilateral ovotestes, with ovarian follicles adjacent to seminiferous tubules and no OCT3/4‑positive germ cells. Postoperatively, estradiol levels initially decreased but later showed intermittent fluctuations in parallel with testosterone, suggesting hormonal activity from a small residual ovarian remnant. Gynecomastia gradually regressed, bone mineral density remained normal, and serial testicular MRI findings were stable. This case demonstrates that even minimal residual ovarian tissue can remain hormonally active after testis‑preserving surgery in ovotesticular DSD and influence pubertal hormonal dynamics, highlighting the importance of careful long‑term postoperative surveillance with hormonal evaluation and targeted imaging.