O-13 PAPILLARY THYROID CARCINOMA IN STRUMA OVARII: A RARE CASE REPORT
Authors: Sünbül Buşra , Güney Sedat Can , Akçura Can , Alkan Samet , Özdemir Nilüfer , Mavili Hanife Seda , Tarhan Serdar , Hekimsoy Zeliha 
Published: January 2025

Abstract

Introduction
Struma ovarii is a subtype of mature teratoma characterized by the presence of predominantly thyroid tissue (&gt;50%) [1]. This condition is usually benign, with malignant transformation occurring in only 0.5-5% of cases, requiring management similar to that of thyroid cancer. The most common malignancy found in struma ovarii, similar to the thyroid gland, is papillary thyroid carcinoma (PTC) [2]. Here, we report a case of a 73-year-old woman with papillary thyroid cancer in struma ovarii.

Clinical Case
A 73-year-old female patient, who was admitted with abdominal pain, underwent bilateral salpingo-oophorectomy due to 4 and 5 cm lesions thought to be hemorrhagic cysts on her right and left ovaries. Pathology result revealed a 2.2 cm teratoma in the left ovary. In the sections, in addition to struma ovarii (&gt;90%), areas of mature teratoma differentiated in the direction of the ectoderm were observed. Two papillary carcinoma foci of 1 cm and 0.5 cm in diameter were detected within the struma ovarii, but no lymphovascular invasion or capsular involvement was observed (Picture 1). In the right ovary, only areas of mature teratoma (struma ovarii) consisting of benign thyroid tissue were seen. Her comorbidities included Type 2 Diabetes Mellitus, Stage 3 Chronic Kidney Disease and Hepatitis B virus carriage. Thyroid ultrasonography result showed normal thyroid gland size and heterogeneous parenchyma with decreased echogenicity. PET/CT scan showed no pathological FDG uptake in the body in favor of malignancy. Laboratory results were given in Table 1. The patient was evaluated by the thyroid council; the stage was calculated as T1a(m)N0M0, AGES and MACIS scores were considered as low risk and a follow-up decision was made for the patient. Routine thyroid and neck ultrasonography along with abdominal and lung imaging were recommended. TSH level was planned to be maintained between 0.5-1 uU/mL and annual thyroglobulin follow-up was planned.

Conclusion
The primary treatment for malignant struma ovarii is the surgical removal of the tumor. Additional therapies, such as thyroidectomy and radioiodine, may be required depending on the presence of metastatic disease and the risk of recurrence [2]. In cases with a low risk of recurrence, as in our patient (no extraovarian extension or distant metastases), most authors recommend levothyroxine to suppress TSH to the lower limit or slightly below normal, along with annual serum thyroglobulin monitoring. Severe elevations in thyroglobulin may indicate recurrence or metastatic disease. Long-term monitoring (at least 10 years) of serum thyroglobulin is necessary for patients with malignant struma ovarii. If the biochemical evidence of persistent or recurrent disease is found, appropriate imaging, including the pelvis, should be performed [3].
Financial disclosures: None
Funding resources: NoneFigure 1:Histological and radiological findings of the patient Table 1:Laboratory results