Endocrine Abstracts

Struma ovarii is a form of mature teratoma, a rare germ cell tumor, containing more than 50% thyroid tissue. Malignancy is uncommon. Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) inside struma ovarii was never described. A 32 y.o. female with previous history of ovarian cysts was admitted in the emergency room with painfull acute abdominal distention. The MRI revealed a right adnexal mass, predominantly cystic with 82x66x80 mm and surrounding oedema. Suspecting of right ovarian torsion, exploratory laparotomy was performed. The torsion was confirmed and the adnexal mass removed. Histopathologic examination showed mature thyroid follicles with abundant colloid in more than 50% of the tissue - consistent with struma ovarii - and a 1 cm area of NIFTP tumor. Thyroid ultrasound was normal and laboratory exams (thyroid function and thyroglobulin levels) within reference range. Malignant struma ovarii is a rare clinical entity that poses a therapeutic challenge, as there is no ’gold standard’ of care. NIFTP is an encapsulated or clearly delimitated, noninvasive neoplasm with follicular growth pattern and nuclear features of papillary thyroid carcinoma, that has an excellent prognosis in thyroid gland, but with yet unknown/uncharacterized behavior as struma ovarii. Of our knowledge, this is the first reported NIFTP in a struma ovarii. The patient is being kept under surveillance by the mutidisciplinary team.