Malignant struma ovarii with synchronous primary papillary thyroid cancer in the neck: A case report and literature review

Malignant struma ovarii (MSO) with synchronous primary thyroid cancer in the neck is extremely rare and lacks a treatment consensus. A 44-year-old woman presenting with a left ovarian cyst was admitted to Peking Union Medical College Hospital (Beijing, China) Ultrasonography showed a 6 cm solid-cystic left ovarian mass with plentiful blood signals. Other notable findings were an elevated CA125 level and a suspected malignant thyroid nodule. A unilateral salpingo-oophorectomy (USO) was conducted, and the surgical pathology was papillary thyroid cancer (PTC) arising in a struma ovarii. The patient underwent a total thyroidectomy and cervical lymph node dissection, and the pathology of the right lobe nodule was follicular-variant PTC without capsule invasion or lymph node metastasis (5 mm; pT1aN0M0). No further adjuvant therapy was administered. The serum thyroglobulin value was normal before surgery and was undetectable after thyroidectomy. During regular follow-up examinations over 4 years, the patient remained well with no evidence of disease (NED). In a literature review, another 13 cases of MSO coexisting with cervical thyroid cancer that had reported outcomes were found. The MSO was confined to the ovary in all cases. A total of nine patients received radioiodine therapy (RAI) treatment after total thyroidectomy. Two patients relapsed and were successfully cured with RAI after the initial surgery Only one patient died due to another disease, while 11 patients showed NED and the remaining patient was alive with the disease after a median follow-up time of 2 years. This data suggests that USO with personalized RAI may be a preferred option for MSO confined to the ovary plus synchronous primary thyroid cancer due to the conferred satisfactory prognosis.