Malignant Struma Ovarii: An Analysis of 88 Cases, Including 27 With Extraovarian Spread

Abstract

Struma ovarii that display extraovarian spread or later recurrence is exceedingly rare. Among 88 patients with "malignant" struma ovarii followed for prolonged periods, several features helped to predict the adverse clinical course. Adhesions (graded 2 to 4+), peritoneal fluid (> or =1 L) or ovarian serosal rent were worrisome features, occurring in 74% of 27 biologically malignant tumors but only 10% of 61 clinically benign tumors. The size of the strumal component rather than the overall size of the ovarian teratoma also had some predictive value. Tumors with a strumal component < or =6 cm recurred rarely (7%), whereas 33% of the consult and 88% of the literature cases > or =12 cm were clinically malignant. Except for a papillary pattern or poorly differentiated cancer, no microscopic feature reliably predicted the clinical outcome, including those typically associated with malignancy in primary thyroid tumors. Among the consult cases, 7% with histologic follicular adenomas and 29% with papillary carcinomas were clinically malignant. Unequivocal vascular invasion was rare, precluding assessment of its effect. Optically clear nuclei, when extensive, were useful to diagnose papillary carcinoma, but were present nevertheless in smaller numbers in both macrofollicular and microfollicular adenomas. Eight tumors confined initially to the ovary (stage 1) recurred. Papillary carcinomas recurred earlier (average 4 y) than follicular adenomatous neoplasms (average 11 y, range: 1-29 y). Overall, the survival rate for all patients was 89% at 10 years and 84% at 25 years, indicating the need for routine long-term follow-up.

Usefulness of 131I-SPECT/CT and 18F-FDG PET/CT in Evaluating Successful 131I and Retinoic Acid Combined Therapy in a Patient with Metastatic Struma Ovarii

“…Malignant struma ovarii is a very rare disease [9][10][11][12]. The clinical course of extraovarian spread and the gold standard therapy have not been fully established.…”

Two Cases of Malignant Struma Ovarii with Metastasis to Pelvic Bone

“…For malignant struma ovarii, the grade or histological type of carcinoma does not seem to be associated with the tendency for adverse outcomes [2]. Histologically, malignant or benign strumas can metastasize [2,6,20]. Features such as grade 2 to 4+ dense adhesions, large strumal size (≥12 cm), or peritoneal fluid (≥1 liter) can be suggestive of a higher likelihood of extraovarian spread or recurrence [20,21]; however, no single histologic or clinical feature reliably predicts which tumor will be biologically malignant.…”

Peritoneal dissemination of follicular carcinoma arising from struma ovarii in a pregnant woman

“…Histologic malignancy arising from struma ovarii has been rarely reported and its occurrence is less than 5% in struma ovarii. Most histologic malignancies arising from struma ovarii are papillary thyroid carcinoma, and account for 70%−85% of total cases [3,4]. Follicular carcinoma of histologic malignancy arising from struma ovarii is extremely rare.…”

“…In the cases of histologic malignancy, however, a clinically favorable course has been reported frequently despite dissemination to other sites. Even in cases in which a malignancy was present on histology, there was a good prognosis with a 10-year survival of 81% and a 25-year one of 60% from malignant struma ovarii of all cell types [4]. In summary, malig- A B KJOG Vol.…”