8016 Resolution of Refractory Hypoglycemia Following Pancreatic Solitary Fibrous Tumor Resection

Abstract

Abstract Disclosure: M.E. Horowitz: None. S. Stefan: None. Introduction: Solitary fibrous tumors (SFT) are exceptionally rare mesenchymal tumors, accounting for only 3.7% of all cases of soft-tissue sarcoma with an incidence of 0.35 cases per 100,000 persons per year. SFT may arise in various anatomical locations, approximately 30% occuring in the abdomen. SFT can manifest with paraneoplastic syndromes, with the most commonly described being non-islet cell hypoglycemia. We present a case of refractory hypoglycemia which resolved following the resection of a large pancreatic SFT. Clinical Case: A 75-year-old male with a history of hypertension presented from oncology clinic with hypoglycemia. Two weeks prior, a 26cm mass of the pancreatic head was identified after he presented to the hospital for one month of abdominal pain and distention, and biopsy of the mass confirmed an SFT. The patient complained of nighttime weakness, confusion, nausea, vomiting, and urinary incontinence for two nights prior to arrival. During this time, the patient had multiple fingersticks showing hypoglycemia below 70 mg/dL, the lowest at 37 mg/dL. On arrival, fingerstick glucose was 38 mg/dL and serum glucose was 27 mg/dL, with a c-peptide level of 0.28 ng/mL (1.00-4.00 ng/mL). Despite hypoglycemia, he was asymptomatic at the time of presentation, indicating hypoglycemia unawareness. Investigation into the cause of hypoglycemia included normal morning cortisol levels, normal thyroid function tests, and normal liver and renal function tests. Further assessment for paraneoplastic disease was conducted, revealing an IGF1 level of 36 ng/dL (5-34 ng/dL) and IGF2 241 ng/dL (267-616 ng/dL), with a ratio of IGF2:IGF1 of 6.7:1. He underwent surgical removal of the large abdominal mass with distal gastrectomy and Billroth-I reconstruction. Pathology was consistent with a 34cm retroperitoneal SFT, STAT6 positivity, and negative margins. Following surgery, the patient did not experience any further hypoglycemia or related symptoms, and glucose ranged 78-135 mg/dL through discharge. Clinical Lessons: Refractory hypoglycemia resulting from a tumor's production of IGF2 is a rare paraneoplastic syndrome known as Doege-Potter Syndrome. This syndrome is observed in fewer than 5% of patients with SFT. The first documented case of hypoglycemia in a patient with "fibrous sarcoma" dates back to 1930. To establish a diagnosis, a ratio of IGF2:IGF1 exceeding 3:1 is suggestive of tumor-mediated production, while a ratio exceeding 10:1 is considered diagnostic. A positive immunohistochemical stain for STAT6 confirms the diagnosis. Patients with these tumors should be routinely monitored for hypoglycemia and related symptoms. Presentation: 6/3/2024