Endocrine Abstracts

Introduction: Doege-Potter syndrome (DPS) is a rare paraneoplastic syndrome consistent in non-islet-cell tumor hypoglycemia associated with solitary fibrous tumor (SFT). Pathogenesis of hypoglycemia has been attributed to the production of insulin-like growth-factor-2 (IGF-2) by tumor cells. We report two DPS patients with metastatic extrapleural SFT.

Case 1: A 42-year-old man with SFT of the mesocolon that had been operated in 2010, presented with metastatic disease (lung, liver, kidney and peritoneum) 4 years later. He was not diabetic and took no medications. From 2015 to 2018 he received 2 lines of systemic therapy (pazopanib and doxorubicin). In May 2018 he had progressive disease (PD) and entered in a phase-1 clinical trial with anti-PD-L1 immunotherapy. Computed tomography (CT) in August 2018 showed stable disease (SD) after 3 cycles of treatment. In September 2018 he complained of severe fasting hypoglycemia (blood glucose: 28 mg/dl) requiring emergency treatment at home. Previous fasting glucose level was always in the normal range. Electrolytes, kidney, liver, pituitary function tests and hemoglobin A1c were normal. Low serum IGF-1 [4.8 nmol/l; normal range (NR): 9.8–28.3 nmol/l), C-peptide [0.1 nmol/l (NR: 0.26–1.44)], and insulin [4.3 pmol/l (NR: 17–120)] concentrations with high serum IGF-2 [734 ng/ml (NR: <700)] concentrations and high IFG-2/IGF-1 ratio [20 (NR <10)] were detected. A new CT in October 2018 showed progression in neck lymph nodes. Prednisone (0.8 mg/kg per day) was started, leading to hypoglycemia resolution.

Case 2: A 65-year-old-man, without any personal history of interest and no medication, was diagnosed with SFT of the prostate and operated in 2009. He presented with metastatic lung disease in January 2017 and he underwent surgery. After PD, he was treated with 3 different systemic therapy (doxorubicin, pazopanib and dacarbazine + gemcitabine). A CT in November 2018 showed PD with metastases in the pancreas. In January 2019 he went to emergency because of dizziness and behaviour alterations secondary to hypoglycemia (blood glucose: 34 mg/dl). Hemoglobin A1c: 5.7%, serum cortisol and thyroid function were normal. Low serum concentrations of GH (< 0.05 mcg/l, NR <3.5), insulin (<6 pmol/l), C-peptide (0.05 nmol/l) and IGF-1 (5.3 nmol/l) were detected. Serum IGF-2 is ongoing. He received treatment with prednisone (0.7 mg/kg per day) with resolution of the hypoglycemia.

Conclusion: In the evaluation of patients with hypoglycemia and SFT a paraneoplastic syndrome induced by IGF-2 should be considered. High dose glucocorticoid therapy seems appropriate to relieve hypoglycemia.