Bilateral highly differentiated follicular carcinoma of ovarian origin with extensive abdominal metastasis: A case report

RATIONALE: Highly differentiated follicular carcinoma of ovarian origin (HDFCO) represents an exceptionally rare subtype of malignant struma ovarii. Despite its histologically indolent appearance, it retains metastatic potential. Early diagnosis, optimal management, and follow-up protocols can significantly reduce recurrence rates. PATIENT CONCERNS: We report a 38-year-old female who was admitted to the hospital with lower abdominal pain for 1 month. DIAGNOSES: Preoperatively, the patient underwent pelvic ultrasound and computed tomography scans, which revealed multiple nodules and masses in the bilateral adnexal regions and abdominal cavity. The definitive histopathological diagnosis confirmed HDFCO. INTERVENTIONS: The patient underwent total hysterectomy, bilateral adnexectomy, part of the greater omentum, pelvic mass excision and pelvic lymph node dissection, followed by total thyroidectomy and radioactive iodine therapy. OUTCOMES: The patient had an uneventful postoperative recovery. Serial measurements of serum thyroglobulin over the subsequent 3-year follow-up period consistently remained within the normal limits and showed no rising trend. Furthermore, all semiannual radiographic evaluations identified no signs of recurrence. LESSONS: For the rare HDFCO, total thyroidectomy combined with radioactive iodine therapy should be considered following radical surgery to reduce the risk of recurrence. Meanwhile multidisciplinary collaboration is essential for the management of rare cases.