Severe Recurrent Hypoinsulinemic Hypoglycemia in a Patient with Malignant Spindle Cell Neoplasm

Presentation Number: MON 288
Date of Presentation: April 3rd, 2017

Amie Ogunsakin*1, John Jasper2, Holly Hilsenbeck3 and Ebenezer A Nyenwe1
1Division of Endocrinology, Diabetes & Metabolism, Memphis, TN, 2Division of General Internal Medicine, Memphis, TN, 3Methodist University Hospital, Memphis, TN

Abstract

Background: Malignant spindle cell tumors are a form of mesenchymal tumors and account for less than 1% of all invasive lung malignancy. Non islet cell tumor hypoglycemia is rare and can occur in tumors of mesenchymal origin, classically retroperitoneal fibrosarcoma and intrathoracic solitary fibrous tumor. These tumors elaborate high levels of complete IGF2 and incompletely processed IGF2, which is the main mechanism for hypoglycemia. We here report a case of severe recurrent hypoglycemia in a patient with intrathoracic malignant spindle cell neoplasm without elevated IGF2 level.

Clinical case: A 49 year old non diabetic female who developed acute confusional state at about 3 AM, and was found to have capillary blood glucose of 30 mg/dl by emergency medical service. She was treated with 25 grams of 50% dextrose administered intravenously and she recovered full consciousness. She reported a 30 lb weight loss within the past year and a 3 month history of diaphoresis, dizziness, and palpitations at night. She admitted to alcohol intake, tobacco and occasional marijuana use. Physical examination revealed normal vital signs, her BMI was 23.9; she had advanced finger clubbing, and decreased breath sounds in the right hemithorax. While hospitalized she had recurrent episodes of nocturnal hypoglycemia.

Laboratory testing revealed low insulin 0.1(4.2-27.9 milliunit/L), proinsulin <5.0(<=18 pmol/L) and C peptide 0.11(0.8-3.80 ng/ml) levels at a serum glucose of 20 mg/dl; she had adequate response to ACTH stimulation test and her IGF 2 level was 329 ng/ml (267-616 ng/ml). Thyroid function tests were normal with TSH of 1.5 (0.35-3.75 mcIU/ml) and FT4 1.1(0.76-1.46 ng/dl). CT revealed a mass in the right hemithorax measuring 17 x14.1x 13.7 cm. CT abdomen/pelvis, MRI brain and nuclear medicine bone scan were normal. She underwent a CT guided biopsy of the mass, the pathology of which showed malignant spindle cell neoplasm. Euglycemia was maintained by frequent ingestion of snacks and complex carbohydrate meals.

Conclusion: Malignant spindle cell tumors are a subset of mesenchymal tumors and can be more definitively characterized by immuno-histochemical staining. The mechanisms of hypoglycemia in non islet cell tumor hypoglycemia, include the over expression and production of IGF2 and incompletely processed IGF 2, which in large concentrations binds to insulin receptors leading to hypoinsulinemic hypoglycemia. Other mechanisms of action include increased glucose utilization by these tumors which are usually large as well as attenuated counter regulatory mechanisms to hypoglycemia. Hypoglycemia in our case could be due to incompletely processed IGF 2 in circulation, despite a normal serum IGF 2 level. The definitive treatment for hypoglycemia in these cases is surgical excision of the tumor, however somatostatin analogues, and steroids have also been utilized in cases of refractory hypoglycemia.

 

Nothing to Disclose: AO, JJ, HH, EAN