A Rare Presentation of the Syndrome of Inappropriate Antidiuretic Hormone in a 12-Year-Old Girl as the Initial Presentation of an Immature Ovarian Teratoma.

BACKGROUND: Immature ovarian teratoma is very rare in childhood. We report on a 12-year-old girl with immature ovarian teratoma who presented initially with syndrome of inappropriate antidiuretic hormone.

CASE: A 12-year-old girl presented with acute abdomen and distention. Initial laboratory tests showed hyponatremia (sodium, 123 mmol/L), that did not respond to fluid management. Computed tomography imaging showed a 15 cm × 9 cm × 20 cm mass in the right ovary with multifocal internal fat, and dystrophic calcifications. She underwent exploratory laparotomy with a right salpingo-oophorectomy, omentectomy, and peritoneal stripping. The pathology revealed metastatic immature teratoma. Hyponatremia resolved soon after the surgery.

SUMMARY AND CONCLUSION: Although a rare diagnosis, immature ovarian teratoma must be considered in a girl who presents with abdominal mass and hyponatremia.