SIADH associated with ovarian immature teratoma: a case report.

Immature teratoma in association with SIADH is rare. A 17-year-old patient presented with a pelvic mass and serum sodium concentration of 121 mmol/l. Subsequent investigation confirmed SIADH and grade 2 ovarian immature teratoma. No other causes of SIADH were found apart from the immature teratoma. There was no further recurrence of SIADH after the curative surgery and chemotherapy. We postulate that immature teratoma consists of neurohypophyseal structures which account for the ADH release.