Session: SAT 429-448-Thyroid Neoplasia & Case Reports
Poster Board SAT-439
In 2008, at age 14, AB was found to have a benign cystic teratoma in the left ovary. In 2010, SO was resected from the contralateral ovary. In 2012, a third surgery revealed numerous omental lesions with a benign thyroid follicular appearance, no nuclear features of papillary carcinoma(PTC) or invasion leading to the diagnosis of "peritoneal strumosis". She returned post-operatively with abdominal pain. CT revealed a left 12X8X11 cm adnexal mass and multiple peritoneal nodules. Debulking surgery was performed and tumor was found in spleen, abdominal wall, urinary bladder and rectum.
Immunohistochemistry was positive for thyroglobulin(TG) and TTF-1. Thyroid function tests were normal, TG=229 ng/ml (2-35), anti-TG Ab were absent and CA125=64 U/ml(<21). No mutations in BRAF, RAS or TP53 were identified.
Thyroidectomy followed by 131I ablation is planned.
SO is uncommon; it is found in 2% of cystic teratomas of which only 5% are malignant. Metastasis from malignant SO is rare. The presence of histological features of PTC have been used to identify malignant potential in SO. When this is absent, cancer is diagnosed by the identification of invasion or by the presence of thyroid follicles in ectopic loci. In recent reports genetic markers of thyroid cancer have been applied in attempts to identify the malignant nature of the tumor.
Controversy exists regarding the malignant nature of "peritoneal strumosis". Some believe that benign thyroid tissue from SO can spread to peritoneum and it should not be considered as malignant; others consider the presence of ectopic thyroid follicular cells to indicate malignancy.
Malignant SO has a significant potential for recurrence and mortality. With the advent of molecular diagnostic tests, there is the possibility that the presence of thyroid cancer associated mutations in SO can lead to the early diagnosis of cancer and impel more aggressive therapy. To date, no molecular markers associated with thyroid cancer have been identified in our patient; further analysis continues. We will review the emerging data concerning the molecular diagnosis of malignant SO.
Nothing to Disclose: JT, RB, DSR, YEN, WG, PL, NM, KHH
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