Struma ovarii is a rare, monodermal, ovarian teratoma. The common presentation is abdominal, with pelvic mass and pain, traditionally managed by gynaecologists. The malignant form is extremely rare and consists of differentiated thyroid cancer. It is rare for struma ovarii to present with features of hyperthyroidism. We present two unusual cases of struma ovarii and discuss the role of the thyroid surgeon in their management.

The first case involved a 40-year-old woman with a two-month history of swelling in the lower abdomen. Investigations revealed a mass arising from the left ovary. Surgery revealed a follicular carcinoma arising in a struma ovarii. She underwent a total thyroidectomy prior to radio-iodine therapy. The second case involved a 60-year-old woman who underwent thyroidectomy for thyrotoxicosis. Three months post-operatively, she remained thyrotoxic despite stopping thyroxine. A whole body radio-iodine scan revealed high uptake in the left ovary. Histological analysis of the resected ovary showed benign struma ovarii.

These two cases highlight the diagnostic and therapeutic role of thyroid surgeons in the management of benign and malignant forms of struma ovarii.