A 26-year-old woman with a 6 cm right ovarian mass presents with palpitations, weight loss, and tremor. Thyroid function tests reveal suppressed TSH with elevated free T4. Neck examination and thyroid ultrasound are normal. The most likely diagnosis is:
- A Struma ovarii ✓
- B Dysgerminoma
- C Yolk sac tumour
- D Ovarian carcinoid
Correct answer: A. Struma ovarii
Explanation
Struma ovarii is a monodermal mature teratoma composed predominantly of functioning thyroid tissue. It can secrete sufficient thyroid hormone to cause clinical thyrotoxicosis with a normal neck thyroid on imaging. Ovarian carcinoid causes flushing and diarrhoea rather than thyrotoxicosis, and germ cell markers such as AFP and LDH are normal in struma ovarii.
Reference: Williams Gynecology, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.