Paraneoplastic Insulin Resistance Syndrome: a case of Fibromatosis (Desmoid Tumour)

Abstract

Introduction: Paraneoplastic endocrine syndrome such as hypercalcemia in malignancy is well-known. However, paraneoplastic insulin resistance is rarely described and its management is challenging. Case history: A 33 years old teetotal gentleman with BMI of 37.5 kg/m2 and histological diagnosis of desmoid tumour presented with osmotic symptoms, weight loss, hyperglycemia and normal ketones. He was hemodynamically stable with no clinical or biochemical evidence of diabetic ketoacidosis. He had acanthosis nigricans. There was no previous history of diabetes or genetic disease. He had extensive excisional surgery to remove the intra-abdominal desmoid tumour followed by chemotherapy. His father had type 2 diabetes controlled with metformin.

Investigations: HbA1c = 142 mmol/mol, c-peptide = 2.91nmol/l[0.34 –1.8], insulin = 55.3 miu/l [2.0-25.0] and random glucose = 26.8 mmol; interleukin 6 = 8.8 pg/ml (0.0-7.0). Diabetes autoantibodies and coeliac screen were negative. Cholesterol = 4.7 mmol/l, triglycerides = 2.9 mmol/l and HDL = 0.9 mmol/l. Full blood count, renal function and thyroid profile were normal. ALT = 151u/l; ultrasound scan showed fatty liver and liver biopsy confirmed severe steatosis with mild steatohepatitis. Results and treatment: Weight loss and osmotic symptoms warranted the initiation of insulin therapy in addition to metformin. Total daily insulin dose was 130 units daily. Semaglutide was added considering its effect on liver fat. Fasting blood glucose fell from 20 mmol/l to 6 mmol/l; ALT fell from 151u/l to 33 u/l; HbA1c fell from 140 mmol/mol to 40 mmol/mol within 7 months. The future plan is to wean off all medications and commence strict caloric management in a multidisciplinary setting.