[Struma ovarii, a rare ovarian tumor]

Teratomas, which consist only or predominantly of thyroid tissue, are termed struma ovarii. Two cases are reported, where after previous strumectomy the histologic diagnosis was struma ovarii. Because of postoperative TSH-rise hormonal activity can be assumed. The proper diagnosis is seldomly made preoperatively, this could be done by abdominal scintigraphic imaging of radioiodine uptake in the tumour.