Hypoglycemia Mediated by Paraneoplastic Production of Insulin like Growth Factor-II (IGF-II) by Renal Malignant Solitary Fibrous Tumor

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 326-337-Hormone-Dependent Tumors
Bench to Bedside
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-334
Ameer Khowaja*, Brianna Johnson-Rabbett, John P Bantle and Amir Moheet
University of Minnesota, Minneapolis, MN
Background: Paraneoplastic production of IGF II is an important consideration in patients with suspected non-islet cell tumor hypoglycemia (NICTH). Its production has been described in desmoplastic small round cells, gastrointestinal stromal cells, hepatocellular carcinoma, prostate, adrenal, mesothelioma, hemangiopericytoma and non-islet cell pancreatic tumors. We present a case of IGF-II induced hypoglycemia from a renal malignant solitary fibrous tumor.

Clinical Case: A 60 year old male presented complaining of sweating, anxiety, inability to concentrate and non specific visual changes for 18 months. His symptoms were determined to be due to recurrent episodes of hypoglycemia. He was, subsequently, referred to Endocrinology clinic for further management. Because of frequent meals to prevent hypoglycemia, he had gained 30 lbs over the last 12 months.  He denied postprandial symptoms and did not have history of gastric surgery or liver dysfunction. On physical examination no significant abnormalities was detected.

Differential diagnoses considered and excluded were medication induced hypoglycemia, Insulinoma (blood glucose 35 mg/dL with appropriately suppressed insulin and C-peptide levels), liver disease, pheochromocytoma, hypothyroidism, adrenal insufficiency and growth hormone related disorder.

The patient’s IGF-II level was found to be 2215 ng/mL (reference: 414 – 1248 ng/mL). An undectable IGF-I level was also noted. He underwent CT scan of the abdomen which showed an 18 cm heterogeneous mass in the right kidney arising from mid to upper pole. He underwent a right sided nephrectomy. Histopathology showed a malignant solitary fibrous tumor, 17.4 x 13.3 x 11.3 cm, with spindled to epithelioid cells and focal high-grade nuclear atypia. The cell proliferation marker, Ki67 index of the tumor was increased. The tumor was positive for CD34, CD99 and Bcl-2 consistent with diagnosis of malignant solitary fibrous tumor.  Follow up IGF II levels were 654 and 563 ng/ml 1 and 8 months after surgery. He did not experience further episodes of hypoglycemia and was able to lose 10 lbs over next 6 months.

Conclusion: Paraneoplastic production of IGF II leading to hypoglycemia is rare but important to consider in patients with NICTH. It has been associated with tumors of mesenchymal, epithelial, hematopoietic and neuroendocrine origin. Prompt diagnosis is of paramount importance because of risk of metastasis in malignant tumors and hypoglycemia associated complications.

Nothing to Disclose: AK, BJ, JPB, AM

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