6712 Intractable Hypoglycemia: A Clue to Tumor Diagnosis

Abstract Disclosure: N. Kharkongor Chengappa: None. E.I. Krug: None. Background: Non-Islet Cell Tumor Hypoglycemia (NICTH) known as Doege-Potter syndrome, is a rare paraneoplastic syndrome of hypo-insulinemic hypoglycemia caused by excessive production of partially processed IGF-II from a solitary fibrous tumor (SFT).We present a case of a patient admitted with intractable hypoglycemia leading to the diagnosis and treatment of a large pelvic SFT. Clinical Case: A 59-year-old male with type 2 Diabetes Mellitus on metformin mono therapy, was admitted after he collapsed at work and was found to have blood glucose (BG) of 22 mg/dl. He was previously in his usual state of health except for an increase in his shoe size over the past year. Physical examination revealed coarse thick skin, large coarse bullous nose, enlarged fingers and a non-tender, firm abdomen with no obvious organomegaly. Laboratory results including CBC, CMP and thyroid function were normal. ACTH stimulation test revealed normal adrenal function. Hypoglycemic drug screen and insulin antibodies were negative. During a hypoglycemic event (BG of 45mg/dl) he had C-peptide level < 0.1ng/ml, beta-hydroxybutyrate levels of <0.05 and insulin level <0.4uIU/ml, indicating non-insulin mediated hypoglycemia. IGF-I and IGF-II levels were ordered. Due to a concern for paraneoplastic etiology of hypoglycemia. CT scan revealed a 20 cm solid mass, filling most of the pelvis and extending into the lower abdomen. Further investigations revealed normal PSA, CEA, CA19-9 and undetectable hCG and AFP levels. MRI confirmed a presence of 23 cm pelvic mass with few areas of central necrosis, extending into the lower abdomen. CT-guided biopsy revealed spindle cell neoplasm consistent with SFT. The patient underwent pelvic mass resection. Postoperatively, hypoglycemia resolved with BG readings of 138mg/dl to 178mg/dl. Surgical pathology results confirmed malignant SFT with positive STAT 6 and CD34 markers. IGF-II level obtained prior to surgery was markedly elevated at 2029 ng/ml (38-267 ng/mL). Conclusion: NICTH was described in 1930 by KW Doege and RP Potter. Less than 5% of patients with SFTs develop NICTH. Diagnosis requires manifestation of Whipple's triad, low insulin, pro-insulin and C-peptide levels, elevated IGF-II levels, or an IGF-I/IGF-II ratio>2, and the identification of the tumor. Positive immunohistochemical stain of the tumor for STAT6 confirms the diagnosis. Management involves resection of the tumor when feasible or debulking. For higher-risk tumors, radiation therapy may be considered. In inoperable cases, glucocorticoids, recombinant hGH and glucagon are recommended for palliation of hypoglycemia. Octreotide and Diazoxide are ineffective in NICTH. References: Soumerai TE et al. Case 20-2023: A 52-Year-Old Man with a Solitary Fibrous Tumor and Hypoglycemia. N Engl J Med 2023;388:2467-77. DOI: 10.1056/NEJMcpc2300899 Presentation: 6/1/2024