Successful Surgical Treatment of a Recurrent Pelvic Solitary Fibrous Tumor of Uterine Origin Accompanied by Doege-Potter Syndrome: A Case Report

BACKGROUND Solitary fibrous tumors (SFT), rare soft-tissue neoplasms, are usually found in the thoracic cavity, and a uterine origin is extremely rare. SFTs with insulin-like growth factor-II (IGF-II) production induce non-islet cell tumor-induced hypoglycemia (NICTH), referred to as Doege-Potter syndrome. CASE REPORT A 70-year-old woman presented with urinary retention, and imaging revealed a huge mass occupying almost the entire pelvic space. She had a history of hysterectomy for leiomyoma of the uterus 7 years earlier. In her present course, she developed hypoglycemia, and NICTH was suspected. Her previous uterine specimen was reexamined, and immunohistochemistry (IHC) revealed the specimen to be CD34-positive and alpha-smooth muscle actin-negative, indicating that the uterine specimen was not leiomyoma but SFT. Therefore, the present pelvic tumor was considered to be a recurrence of SFT with NICTH, namely Doege-Potter syndrome. Surgical resection was performed, and the pathological examination showed the same histologic features as the previous uterine specimen, while IHC revealed the present specimen to be positive for CD34, signal transducers and activator of transcription 6, and IGF-II, consistent with the diagnosis of recurrent SFT with IGF-II production. The patient's hypoglycemia improved after tumor resection. To confirm the IGF-II secretion from the SFT, we conducted immunoblotting of the patient's perioperative serum, with results showing that the strong band of IGF-II in the preoperative serum disappeared after surgery. CONCLUSIONS Because SFTs, especially those with Doege-Potter syndrome, often recur, sometimes with a very long interval, long-term cautious surveillance is required, even after complete tumor resection.