A 31-year-old woman presents with palpitations, tremor and weight loss despite a goitre-free neck examination. Thyroid function tests confirm biochemical thyrotoxicosis. Pelvic ultrasound incidentally shows a 7 cm left ovarian mass. Which ovarian tumour explains these findings?

• A Yolk sac tumour with hepatoid differentiation
• B Dysgerminoma with syncytiotrophoblastic giant cells
• C Mature cystic teratoma composed predominantly of thyroid tissue ✓
• D Mucinous cystadenoma with stromal luteinisation

Explanation

Struma ovarii is a monodermal teratoma in which thyroid tissue constitutes more than half of the tumour. Functional thyroid tissue within the ovary can secrete hormone and cause thyrotoxicosis with no neck goitre. It accounts for about 2 percent of ovarian teratomas and roughly 5 to 10 percent are biochemically hyperfunctional. Dysgerminoma produces LDH, yolk sac tumour produces AFP, neither causes thyrotoxicosis.

Reference: Williams Gynecology, 3rd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.