MON-388 Strumal Carcinoid in a Mature Teratoma: A Rare Ovarian Neoplasm with Thyroid Involvement

Abstract Disclosure: V.A. Mendpara: None. M. Eldib: None. P.P. Rao: None. Introduction: Ovarian carcinoid tumors are the most common neuroendocrine neoplasms of the female genital tract, typically arising in mature teratomas. Strumal carcinoid, a rare monodermal teratoma (0.1% of ovarian malignancies), consists of thyroid tissue with an insular or trabecular carcinoid component. It is borderline malignant and usually managed with salpingo-oophorectomy or oophorectomy. Case Presentation: A 68-year-old female with multiple thyroid nodules and a family history of thyroid and ovarian cancer presented for evaluation. She had no thyroid-related symptoms or history of radiation exposure. Her past medical history included ulcerative colitis, treated with total colectomy and ileostomy, complicated by a portal vein clot due to MTHFR mutation and Factor VIII deficiency. Over the years, she three hernia repairs, later developing bowel obstruction from adhesions and infected mesh, necessitating further surgeries. She had endometrial hyperplasia managed with a progestin IUD. Imaging identified a probable posterior uterine pedunculated fibroid with cystic degeneration, which had increased in size compared to prior imaging. Due to her complex gynecologic history, she underwent fistula repair, mesh removal, total hysterectomy, and bilateral salpingo-oophorectomy. Pathology of the right ovary revealed a mature teratoma with low-grade mucinous epithelial neoplasm and strumal carcinoid measuring 7 cm, while the left ovary had cortical inclusion cysts. Thyroid ultrasound showed a 1.7 cm hypoechoic solid nodule in the lower left thyroid lobe, categorized as TI-RADS 5 and three additional solid nodules requiring follow-up. Fine-needle aspiration (FNA) of the left nodule showed atypia of undetermined significance (Bethesda III) with scant microfollicles, nuclear atypia, and scant colloid, while the right was benign (Bethesda II) consistent with a hyperplastic nodule. The Afirma test was negative. Thyroid function tests and tumor markers were normal, and she was not on thyroid medications. She remains under endocrinology follow-up for thyroid nodules and ongoing surveillance for recurrence or complications.Discussion: Ovarian carcinoids are rare, comprising only 5% of cases, with preoperative diagnosis often challenging due to nonspecific presentation and limited imaging specificity. Most are indolent and managed surgically. Strumal carcinoid, a rare variant with neuroendocrine and thyroid tissue, highlights the need for endocrinological evaluation, especially in patients with thyroid nodules. Multidisciplinary is key for accurate diagnosis and management. Conclusion: This case highlights the importance of endocrine evaluation in ovarian strumal carcinoid. While surgery is the mainstay of treatment, ongoing monitoring is essential. Improved screening and molecular profiling may enhance early detection and outcomes. Presentation: Monday, July 14, 2025