[Struma ovarii]

A case of struma ovarii in which the correct diagnosis was only suspected at the time of surgery is reported. A 131I scintiscan offers the only preoperative means of ensuring diagnosis. Indeed the condition itself is rare and its clinical signs resemble those of a small ovarian cyst, so that preoperative diagnosis may well be mistaken. Hyperthyroidism accompanied by a normally functioning cervical thyroid offers the sole reason for suspecting an adnexal mass or a struma ovarii.