Endocrine Abstracts

Background: Struma ovarii (SO) is the presence of thyroid tissue as a major cellular component in an ovarian tumour.

Case report: A 35-year-old, Caucasian female, asymptomatic and with normal physical examination was submitted to left oophorectomy due to an ovarian mass (8.2×7.0×6.0 cm) detected in routine pelvic examination. Her mother also had history of oophorectomy for an ovarian tumour and partial thyroidectomy for benign thyroid nodule. The histological examination of the mass showed a totally intra-ovarian neoplasia predominantly composed of thyroid tissue (95%) with areas of follicular variant of papillary thyroid carcinoma (FVTPC) which was compatible with malignant SO. She was tested for thyroid function which was normal and thyroid ultrasound revealed a slightly hypoechogenic nodule with 1.7 cm in the right lobe. Fine needle cytology of this nodule was performed and was compatible with FVTPC. She underwent total thyroidectomy and histology revealed a well differentiated thyroid tumour of uncertain malignant potential. No vascular or capsular invasions were recorded. She was treated with ¹³¹I and suppressive doses of levothyroxine and remains asymptomatic, without signs of clinical or biochemical recurrence of thyroid and ovarian tumours. The search for BRAF mutations was negative.

Discussion: Three other cases of synchronous thyroid and ovarian thyroid tumours have been described so far to the best of our knowledge. In this case, since both tumours were confined and no invasion was documented they were probably synchronous tumours instead of metastasis. These two tumours are embryologically related so we cannot exclude a common mechanism of genomic origin that possibly explains the synchronous tumours and even the familiar history.