Context: The post-surgical follow-up of malignant insulinomas is often marked by recurrence after initial remission. However, the criteria for the diagnosis of recurrence of these malignant endocrine tumors are not well defined in the literature, unlike diagnostic of criteria for hyperinsulinemic hypoglycaemia (Cryer 2009). We retrospectively reviewed the criteria that allowed the diagnosis of recurrence in four patients with malignant insulinoma after initial post-operative remission.
Patients and methods: At the initial diagnosis, two patients had a metastatic insulinoma (one in the liver, one in lymph nodes) and two patients had a single tumor whose radiological presentation was benign. After pancreatoduodenectomy (n=4), lymph node resection (n=3) and left hepatectomy (n=1) patients were considered in remission, defined as R0 resection and no clinical or biological post-operative hypoglycaemia.
Results: The recurrence occurred after 14.8±8.5 months (m±S.D.). Three patients had clinical signs of hypoglycaemia, but only one patient had a proved fasting hypoglycaemia (1.26 mmol/l). The remaining three patients did not reach the classical criteria of hyperinsulinemic hypoglycaemia during a 72 h-fast test (n=2) or serial plasma glucose, insulin and C-peptide measurements (every 4 h for 24 h): the lowest plasma glucose levels in these three patients were 3.2, 2.5, and 4.3 mmol/l with concomitant C-peptide levels of 0.3, 0.5, and 0.8 ng/ml, respectively. At the same time, radiological (CT scan n=3, MRI scan n=1) evaluation revealed lymph nodes (n=2) or liver metastases (n=2) attesting recurrence of malignant insulinoma.
Conclusion: After initial post-operative remission, the diagnosis of recurrence of malignant insulinoma cannot be based only on clinical and biological criteria, but CT or MRI scan evaluation is mandatory during post surgical follow-up of such patients.
30 Apr - 04 May 2011
European Society of Endocrinology