Abstract #1412915: Malignant Struma Ovarii - A Rare Disease with Unpredictable Nature and Treatment Option Controversies

Abstract

Struma ovarii is a rare kind of ovarian teratoma which consists of >50% of thyroid tissue. It contributes to 2-5% of all ovarian teratomas. 5-10% of ovarian teratomas undergo malignant transformation. To date, due to its rarity, unpredictable nature and high recurrence rate no consensus have been reached regarding the optimal treatment strategy. Therefore, it is prudent to highlight this rare disease and its management as sharing experiences will further expand the accruing data and helps in reaching consensus regarding its optimal treatment strategy. 42-year-old lady presented in clinic with missed periods. She had no weight loss and hyper or hypo thyroidism related symptoms. Her ultrasound pelvis revealed left ovarian cyst and MRI showed left ovarian dermoid cyst. She underwent left oophorectomy whose biopsy showed malignant struma ovarii having papillary thyroid carcinoma, FIGO stage 1a and BRAF V600 mutation was present. Her thyroid function test, thyroid scan, CT chest and abdomen were normal. She underwent staging laprotomy, right salphingo-oophorectomy, left salphingectomy and total hystrectomy whose biospy was normal. Subsequently total thyroidectomy was done which showed <1cm low grade papillary thyroid carcinoma involving left lobe of thyroid gland, stage pT1a, Nx, Mx. Her stimulated thyroglobulin and antithyroglobulin antibody were normal. Her 6 weeks postop ultrasound neck was normal. She was kept on replacement thyroxine doses. Malignant struma ovarii presents with abdominal pain, menstrual irregularity, bloating, abdominal mass and ascites. At times it may be asymptomatic. Thyroid symptoms are not frequent. Studies demonstrated good survival with malignant struma ovarii. However, its clinical course remains unpredictable with relatively high frequency of recurrences and metastasis irrespective of its morphology which poses difficulty in optimal treatment selection. Mostly aggressive approach including total hystrectomy, bilateral salphingo-oophorectomy, total thyroidectomy followed by radioactive iodine therapy and thyroxine in TSH suppressive doses have been adapted. Though some prefer less aggressive approach. Due to its uncertain nature and scanty data on its management, its optimal treatment is still a matter of debate. Tumor size, molecular profiling and histopathology have been proposed to consider while stratifying risk and selecting treatment approach. Moreover, vigilant followups should be done to detect early recurrence or metastasis so that timely intervention could be done.