Insulinoma: 31 years of tumor localization and excision.

This report is based on 31 years of experience with 116 cases of hyperinsulinism. Six cases had hypertrophy of the islets of Langerhans, 3 had widespead metastasis from malignant insulinomas, and 107 were benign adenoma cases. An immunoreactive insulin to glucose ratio of 0.3 of the peripheral venous blood before operation is of great value in diagnosing hyperinsulinism. Intraoperatively, immunoreactive insulin assay of the portal blood (IRI) is very valuable in determining if an insulinoma remains. The dividing line is 100 microU.ml-1. In localizing the tumor, "differential" PTPC is important before operation. During the operation, fine needle aspiration cytology may assist in ascertaining if the palpable tumor is an insulinoma. Multiple fine needle aspiration cytology examinations can sometimes reveal an insulinoma in an indurated pancreas. Portal vein blood IRI and blood sugar assays may serve to confirm if removal of the insulinoma is complete. Removal of the insulinoma controls hypoglycemia satisfactorily, but the brain damage incurred by prolonged hypoglycemia cannot be significantly altered. Removal of the tumor should be by enucleation, and the raw surface of the pancreas should be drained not sutured.