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Struma ovarii: a rare form of presentation and clinical review

Mature cystic teratomas represent 40–50% of ovarian neoplasias from which 0.3–1% are struma ovarii, the most common monodermic teratoma of the ovary. Struma ovarii, originally described by von Kalden in 1895, occurs more often in countries where goiter is endemic and has maximum incidence in the fifth decade. It is defined as a teratoma in which thyroid tissue comprises more than 50% of the neoplasic tissue and is classified as benign or malign. The malignant form is rare and is thought to represent 5–37% of the cases, although its criteria of definition have not been uniformly accepted. Most patients are asymptomatic, but they can manifest as abdominal distention, pain, signs and symptoms of urinary or intestinal obstruction, infertility, abnormal uterine bleeding, dysmenorrhea and hot flashes (due to steroid hormone production). Ascites is evident in 1/3 of the cases, but it rarely presents as Meigs’ syndrome. In 1/6 of the cases the thyroid gland is augmented. Most benign strumae accumulate iodine and occasionally (5–20%) may even produce significant amounts of thyroid hormones, as they resemble normal thyroid tissue. Strumosis is an entity that is characterized by the surgical findings of peritoneal and omental implants of differentiated thyroid tissue in a patient with benign struma ovarii. It has an indolent clinical course and may result from extraovarian dissemination of a ruptured struma ovarii.