Case Report: Solitary fibrous tumor of the pelvis associated with Doege-Potter syndrome.

Introduction: Solitary fibrous tumor (SFT) is an uncommon mesenchymal spindle cell neoplasm (incidence ~1.4 per million). Although most SFT occur in the thoracic cavity, they can also arise in the retroperitoneum, pelvis, head, and neck. While the majority exhibit benign behavior, approximately 5% are associated with paraneoplastic syndromes, most notably Doege-Potter syndrome (DPS). DPS is characterized by non-islet cell tumor hypoglycemia (NICTH) resulting from tumor hypersecretion of high-molecular-weight insulin-like growth factor 2 (IGF2), which saturates insulin and IGF receptors causing refractory, life-threatening hypoglycemia. Due to nonspecific presentation and low incidence, DPS secondary to pelvic SFT is frequently misdiagnosed, underscoring the need for heightened clinical awareness. Case report: A 56-year-old man presented to the neurology department with acute loss of consciousness, aphasia, and urinary incontinence. He had a 3-year history of hypertension but no diabetes mellitus. Initial laboratory tests showed a blood glucose of 4.76 mmol/L; however, during hospitalization, he developed recurrent severe hypoglycemia, with a nadir glucose of 1.6 mmol/L. Further biochemical evaluation during fasting hypoglycemia revealed undetectable insulin (<0.2 mIU/L) and low C-peptide (0.14 ng/mL). Contrast-enhanced abdominopelvic CT demonstrated a 17.8 cm heterogeneously enhancing pelvic mass causing bladder compression and left ureteral displacement. The patient declined preoperative biopsy. Preoperative euglycemia was maintained with continuous intravenous dextrose infusion, and open en bloc surgical resection was performed. Histopathology and immunohistochemistry (positive for STAT6, CD34, and CD99; Ki-67 8%) confirmed an atypical solitary fibrous tumor. Postoperatively, hypoglycemic symptoms resolved completely, and the patient was discharged on postoperative day 6 without further hypoglycemic episodes. Conclusion: Pelvic SFT with DPS frequently presents with recurrent hypoglycemia or altered consciousness rather than local compressive symptoms. Early recognition of non-islet cell tumor hypoglycemia (NICTH) and prompt cross-sectional imaging are essential for accurate diagnosis. Complete surgical resection is definitive and results in full resolution of hypoglycemia. Given the unpredictable biological behavior of SFT, long-term follow-up is essential. Heightened clinical awareness may improve diagnostic accuracy and patient outcomes.