Late recurrence of a malignant hypoglycemia-inducing pelvic solitary fibrous tumor secreting high-molecular-weight insulin-like growth factor-II: A case report with protein analysis

The present study reports a case of recurrent malignant pelvic solitary fibrous tumor (SFT) that induced non-islet cell tumor hypoglycemia via high-molecular-weight insulin-like growth factor-II in a 72-year-old male patient. The tumor recurred ~12 years after the complete resection of the original mass. The recurrent tumor, which had directly invaded the left ureter and perirectal fat tissue, could not be completely excised due to its fragility and adhesiveness. At 13 days post-surgery, the patient presented with rectal perforation, and an urgent rectal resection and colostomy was performed. Neither recurrence of the tumor nor hypoglycemic symptoms were observed 9 months after the surgery. High molecular weight insulin-like growth factor-II was detected in the serum and tumor specimens by western blot analysis and immunohistochemistry. The present case report suggests that certain SFTs can relapse even ≥10 years after a presumed complete resection of the primary tumor, and that performing a safe and complete resection of these tumors can be challenging, due to their adhesiveness or physical presentation; therefore, the indications for surgery should be considered with caution.