[An ovarian tumor can hide another one].

We report the case of a 33-year-old woman who went under surgery for a cystic mature teratoma. The histological exam found two cysts, one was a mature teratoma and the other was a struma ovarii with a papillary carcinomatous element. Struma ovarii cancerization is seen in 5 to 10% of the cases usually under a papillary carcinoma type. Diagnosis is rarely made before surgery, the patients exceptionally show thyroid symptoms. Histologically, the tumour presents the same way as the one seen in the thyroid gland and BRAF mutations have been reported. The problem concerns ovarian metastases of a thyroid cancer. A normal thyroid check up and normal thyroid tissue close to the tumor in the ovary are in favor for a cancerize struma ovarii. The therapeutic care is not consensual, going from an annexectomy to hysterectomy and bilateral annexectomy. The patients must be followed on long-term with thyroglobulin quantitative analysis for at least 10 years and whole body scintigraphy with iodine 123 to detect relapse or metastases. The prognosis is usually good but precise criteria are still to define.