Endocrine Abstracts

In 2022, a 63 year old woman was referred for assessment of a six month history of gastro-oesophageal reflux symptoms and dysphagia. Upper gastrointestinal (GI) endoscopy was normal apart from mild reflux oesophagitis. A computerized tomography (CT) scan demonstrated a 2 cm nodule medial to the caudate lobe of the liver, a 1.5 cm nodule in the right lung base and two further sub cm nodules in the right lung lobe. In terms of background, the patient had a benign breast lump under surveillance and she had undergone a right sided salpingo-oophorectomy in 2008. Following discussion in the upper GI multi-disciplinary team (MDT) meeting she was referred for biopsies of lung nodule and caudate lobe lesion. The paravertebral biopsy of lung nodule was non-diagnostic and an endoscopic biopsy of caudate lobe lesion was suggestive of metastatic thyroid carcinoma (TTF-1 and thyroglobulin immunostain positive). FDG and DOTATATE positron emission tomography (PET) scans showed no evidence of uptake in thyroid gland but there was uptake in the lung node and in the nodule medial to the caudate lobe. Serum thyroglobulin was 43.1 ug/l with negative anti-thyroglobulin antibody. Thyroid ultrasound showed a 6 x 8 mm exophytic (BTA class U2 i.e. benign) nodule, FNAC confirmed benign cytology (Thy2). Her case was discussed in our central thyroid cancer MDT meeting where it was suggested to review histopathology of the right sided ovary and tube from 2008. This confirmed a large cystic teratoma (weighing 1368 gm) with well-formed thyroid tissue of fetal origin which showed thyroglobulin and TTF1 marker positivity on immunohistochemistry. The patient has undergone total macroscopic removal of the thoracic metastasis and laparoscopic excision of the nodule medial to the caudate lobe of the liver. Histopathology of these samples was similar to the previous atypical thyroid lesion within the mature teratoma of the right ovary, consistent with a diagnosis of metastatic struma ovarii. Although the metastatic disease has progressed slowly, after careful consideration the patient will have thyroidectomy to facilitate radioiodine treatment with a proposed dose of 3.7 GBq. Struma ovarii is a rare ovarian germ cell tumour and comprises only 1.4-2.7% of ovarian tumours. 5-15% of teratomas contain thyroid tissue. The vast majority of struma ovarii are benign, with malignant disease found in less than 5-6% of cases. As struma ovarii is a rare tumour, there is an absence of consensus and guidelines on the management of metastatic disease.