Background: Struma ovarii, defined as containing 50% or more thyroid tissue is rare and accounts for 1% of ovarian tumours. Presentation is non-specific, relating to mass effect. Although the tumour predominantly consists of thyroidal tissue, features of hyperthyroidism occur in <5% of cases. Majority are benign, histological features of thyroid cancer are found in about 510%. Seventy per cent of these are papillary thyroid cancer (PTC). We present a case of struma ovarii with papillary thyroid carcinoma.
Case presentation: A 62-year-old lady presented with abdominal discomfort. Ultrasound pelvis identified a large right sided ovarian mass. CA-125 was elevated, thyroid function tests were normal. At laparotomy, a large impacted tubo-ovarian mass was identified; total abdominal hysterectomy with bilateral salpingo-oophorectomy was performed. Histology revealed a collapsed thick walled cyst with haemorrhage. Immunocytochemistry was in keeping with papillary thyroid cancer arising in struma ovarii. Tumour was classified as FIGO 1C in view of the ruptured cyst wall.
Management: Following discussion at thyroid MDT, total thyroidectomy was recommended to facilitate adjuvant radioactive iodine ablation and exclude associated papillary thyroid cancer as described in literature. Histology of thyroid showed colloid hyperplastic nodule of 5 mm with no evidence of malignancy. Post operatively radioiodine ablation 3.7 GBq was carried out. CT and I131 scan did not identify any metastasis. Stimulated thyroglobulin was <5 (μg/l. She is currently established on levothyroxine with a view to maintaining suppressed TSH.
Discussion: This case demonstrates an uncommon clinical scenario of PTC in struma ovarii and the importance of a multidisciplinary approach in its management. Although there is no consensus on management of patients with malignant struma ovarii, our patient was risk stratified as high risk and hence surgical curative treatment of the primary tumour with total hysterectomy and bilateral salpingo-oophorectomy, followed by total thyroidectomy and radioiodine ablation.