Abstract
Malignant transformation of a mature cystic teratoma (MCT) is an infrequent, often asymptomatic event. We report the first example of a struma ovarii with a focus of follicular variant of papillary thyroid carcinoma (a), mucinous adenocarcinoma (b), and strumal carcinoid tumor (c)—all three arising in one mature cystic teratoma of the ovary. From our reviews, we found limited data to guide management when these malignant foci occur within an MCT. Consideration should be given to thyroidectomy followed by total-body scanning and serum studies for foci of thyroid carcinoma and adjuvant therapy with thyroidectomy and radioablation if residual disease is identified (a). Additionally, extrapolating from data for mucinous adenocarcinomas, consideration could be given to adjuvant chemotherapy after appropriate staging (b). Strumal carcinoid tumors should be treated as tumors of low malignant potential. Observation is appropriate if after complete staging, no invasive implants are noted (c).
Highlights
Mature cystic teratoma (MCT) is not a rare occurrence, accounting for about 20% of ovarian tumors, but malignant transformation of MCT is infrequent [1]
Due to the rarity and resulting inability to design management trials, there is no consensus on the treatment of malignant struma ovarii
Some advocate a post-operative total-body 131I scintiscan to assess for residual malignant disease and trending serum thyroglobulin levels to monitor for recurrence and adjuvant therapy only if these were positive, and this should be used with caution if not in the setting of thyroidectomy as most malignant struma ovarii have poor iodine uptake and thyroid hormone synthesis [1, 15]
Summary
Mature cystic teratoma (MCT) is not a rare occurrence, accounting for about 20% of ovarian tumors, but malignant transformation of MCT is infrequent [1]. Struma ovarii is a rare monodermal ovarian teratoma, diagnosed when a teratoma specimen contains at least 50% thyroid tissue These represent about 2% of MCT and most commonly occur in the fifth or sixth decades of life. Adenocarcinoma, which includes mucinous type, accounts for 6.8% of all malignant transformations of MCT [6]. Primary ovarian carcinoid tumors are very rare and account for fewer than 0.1% of all ovarian carcinomas They can be subdivided into four types: insular, strumal, Case Reports in Obstetrics and Gynecology trabecular, and mucinous. They may occur with or without an associated MCT, and most commonly as a singular subtype, mixed primary ovarian carcinoids have been reported [7]. The mass was found to be a mature cystic teratoma containing three separate and different malignant foci
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