Introduction/Background Ovarian goiter also named as struma ovarii. It is a rare endocrine tumor of the ovary, usually benign, consisting mostly of thyroid tissue.

Ovarian goiter is a rare endocrine tumor of the ovary, usually benign, consisting mostly of thyroid tissue. Malignant transformation is exceptional. The histological diagnosis of malignancy is difficult, especially in the case of well-differentiated tumors. The prognosis is generally favorable except for poorly differentiated or undifferentiated and metastatic tumors. We report the case of an ovarian goiter

The aim of our work is to describe the circumstances of discovery, the positive diagnosis and the therapeutic modalities of malignantovarian goiter.

Methodology 45 years old patient, presented with pelvic pain, evolving for 3 months. clinical examination found an abdominal pelvic mass halfway to the umbilicus. Pelvic ultrasound showed a heterogeneous pelvic mass measuring 60 x 70mm. Pelvic MRI revealed a left lateral-uterine mass, measuring 80 x 60 x 55mm, with predominant fat and tissue content, intensely and heterogeneously enhanced after injection of Gadolinium. This mass had a mass effect on the uterus, which had a normal size. The imaging was therefore in favor of a germ cell tumor. CA 125 was negative, as were the other biological tumor markers. Surgical exploration was performed finding a whitish ovarian mass measuring 7 x 5 cm, with a smooth external surface, brownish aspect, and fleshy on section. An adnexectomy was performed.

Results Papillary thyroid carcinoma with exclusive vesicular differentiation on thyroid goiter, without ovarian effraction, and images of vascular emboli or foci of necrosis.

Conclusion Malignant ovarian goiter is a rare tumor, with an unspecific clinical symptomatology. Histology makes the diagnosis. Treatment consists of radical surgery. Conservative treatment can be done in young patients with a localized tumor, with a project of procreation.

Disclosures Papillary thyroid carcinoma with exclusive vesicular differentiation on thyroid goiter, without ovarian effraction, and images of vascular emboli or foci of necrosis.