Endocrine Abstracts

Introduction: Hormone-secreting teratomas are well described. However teratomas secreting pancreatic hormones are rare, with even fewer cases producing clinically significant effects. We describe possibly the first documented case of hyperinsulinaemic hypoglycaemia due to an insulin-secreting ovarian teratoma.

Case report: A 23-year-old woman presented with transient symptoms of lethargy and weakness. She had used her father’s capillary glucose meter to measure her own blood glucose, recording values of 2.1 and 2.8 mmol/l. Further investigation confirmed a fasting glucose of 2.7 mmol/l, elevated insulin (40.4 mIU/l) and C-peptide (5.6 ng/ml), with a normal cortisol (624 nmol/l) and IGF-2/IGF-1 ratio (<10). Abdominal ultrasound and CT scans revealed a 10 cm cystic teratoma arising from the right ovary, with normal appearance of the adrenal glands and pancreas.

The ovarian mass was removed laparoscopically. Histopathology findings were of a mature cystic teratoma containing teeth, hair, skin, sebaceous material, cartilage and a large, mature, pancreatic tissue component. Within this, immunohistochemistry showed differential expression of insulin, glucagon and somatostatin in islet cells. Hypoglycaemia did not recur post-operatively. The resolution of symptoms following surgical excision suggests that the patient’s hyperinsulinaemic hypoglycaemia was due to ectopic insulin secretion from apparently mature pancreatic tissue within the teratoma.

Conclusions: Ectopic hormone release from teratomas is well described, including AFP from yolk sac-containing teratomas, hCG from pineal teratomas, and, most notably, thyroid hormones from cystic struma ovarii, which may rarely cause thyrotoxicosis. Nevertheless there are few cases of pancreatic hormone-secreting teratomas in the literature, with only a handful causing clinically significant effects. We could not find any other cases of hypoglycaemia secondary to an insulin-secreting ovarian teratoma. In summary, this unusual case demonstrates failure of normal glucose homeostasis secondary to ectopic insulin secretion from an ovarian teratoma, resulting in recurrent hypoglycaemia.