Nineteen cases of insulinoma were treated in this centre between 2003 and 2012 (12 female, 7 male, 5 associated with MEN-1). Of the cohort, 14 had their primary investigation and management here. All presented with symptoms consistent with hypoglycaemia and had a supervised fast demonstrating serum glucose <2.2 mmol/l with inappropriately normal/elevated insulin.
11 of 14 patients proceeded to surgery. Two elderly patients declined further investigation after their fast and CT scan, which identified a lesion in both cases. Conservative management with somatostatin analogues/dietary interventions were successful in managing hypoglycaemia. A third case had radiological evidence of extensive liver metastases and underwent hepatic arterial embolisation along with palliative chemotherapy but died 12 months after diagnosis.
Of the 11 patients who proceeded to surgery, the lesion was localised pre-operatively in each case, all lesions being confirmed as insulinoma on histology. All of these patients were cured of their symptomatic hypoglycaemia with no recurrence to date (follow-up range 3 months9 years). Ten patients had CT as first line imaging, with the lesion identified in eight cases (sensitivity 80%). These lesions were subsequently seen on EUS. Eleven patients underwent EUS and all 11 procedures identified a lesion (100% sensitivity). FNA was carried out in addition to EUS in two cases, cytology demonstrating grade 1 neuroendocrine tumour. Five patients had MRI, with successful localisation in all cases. Coeliac axis angiography yielded a sensitivity of 57% over seven cases. Where this failed to demonstrate a lesion, selective calcium arterial stimulation and venous sampling was successful with 100% sensitivity (four cases, one of which was concordant with the angiography result). Specificity was 100% for all modalities.
Our experience suggests, in our centre, a combination of MRI/CT imaging and EUS following a biochemical diagnosis of insulinoma accurately identifies lesions, facilitating targeted curative surgery.