NON-ISLET CELL TUMOR SECONDARY TO MALIGNANT PHYLLODES TUMOR OF BREAST

Abstract

INTRODUCTION/BACKGROUND
Non-islet cell tumour-induced hypoglycaemia (NICTH) is a rare but important cause of recurrent hypoglycaemia in patients with non-pancreatic tumours. Unlike insulinomas that cause hypoglycaemia through excess insulin secretion, NICTH is associated with large mesenchymal or epithelial tumours producing high-molecular-weight insulin-like growth factor 2 (IGF-2), leading to insulin-independent hypoglycaemia. We report a case of NICTH in a patient with a malignant phyllodes tumour of the breast.

CASE
A 50-year-old female was found unresponsive at home with a blood glucose level of 2.3 mmol/L. She regained consciousness following the administration of IV glucose. She had no history of diabetes or use of glucose-lowering agents. Examination revealed a large, firm 20 × 20 cm left breast mass. Hypoglycaemia work-up showed a random glucose level of 3.0 mmol/L, C-peptide of 35 pmol/L and insulin <2.78 pmol/L, suggesting hypoinsulinaemic hypoglycaemia. IGF-1 was within the normal range. She was treated with glucocorticoids while awaiting surgery. She underwent a left mastectomy, which revealed a 16 × 12.5 × 22.5 cm 7.6-kg malignant phyllodes tumour. Histopathology examination confirmed a malignant phyllodes tumour with high mitotic activity and a high risk of recurrence. An oncology referral was made for adjuvant therapy. At one-month follow-up, she remained asymptomatic with no hypoglycemia.

CONCLUSION
NICTH should be considered in patients with large tumours presenting with hypoglycemia. Corticosteroids may help manage hypoglycaemia before surgery, which remains the definitive treatment. A multi-disciplinary approach is essential for optimal care.