INSULIN SECRETING TUMORS OF THE PANCREAS

Diagnostic monitoring of plasma levels of glucose and insulin during surgery for insulinoma

With serial measurement of blood sugar levels during surgery in three patients with solitary insulinoma, we confirmed the location, then later, the complete elimination of the insulin-secreting tumor. Following vigorous massage of the tumor, blood sugar levels decreased while the levels progressively increased within 20 min following removal of the tumor. Subsequent measurement of simultaneous plasma insulin levels provided further confirmation. Plasma levels of insulin increased in accordance with massage of the tumor. Prior to removal of the tumor, the levels progressively decreased to less than the preoperative levels. For success in detecting slight changes in blood sugar levels secondary to increase or decrease of insulin secretion during surgery for insulinoma, (1) controlled infusion of glucose to keep blood sugar levels around 80 mg/dl and (2) frequent rapid determination of blood sugar levels are considered to be important.

Artificial pancreas as an aid during insulinoma resection

Blood glucose control by an artificial pancreas facilitated the intraoperative management of two patients with insulin-secreting pancreatic islet cell tumors (one had a large adenoma, the other diffuse islet-cell hyperplasia). The artificial pancreas is a glucose-controlled insulin and dextrose infusion system uniquely suited for the control of blood glucose concentrations during surgery. The artificial pancreas produced a stable glycemic baseline before surgery, prevented hypoglycemia during palpation of the pancreas and manipulation of the tumor, and indirectly amplified small decreases in the blood sugar level with large increases in the rate of dextrose infusion. The advantages and limitations of continuous glucose monitoring during surgery and the use of this instrument in locating occult insulin-secreting tumors are reviewed.

Endocrine tumors of the pancreas

A review of 33 patients operated on between 1951 and 1978 for endocrine tumors of the pancreas is presented. The series consists of 25 patients with hyperinsulinism, 6 with the Zollinger-Ellison syndrome, and 2 with the WDHA syndrome. Clinical features and diagnostic problems are discussed. A noticeable feature is that the average time lapse between onset of symptoms and final diagnosis in insulinoma patients has not been significantly reduced during the years covered by this review. This is in spite of the progress made in testing procedures and laboratory methods designed to diagnose hyperinsulinism. Resection of the tumor has been the preferred treatment in insulinoma patients, of whom 22 are still alive. Insulinomas were associated with other endocrinopathies in 3 cases. Patients with the Zollinger-Ellison syndrome had raised serum gastrin levels and increased basal acid output. Four patients are still alive. Two patients had other endocrinopathies. Both patients with the WDHA syndrome died shortly after the operation. One had biochemical evidence of multiple endocrinopathies.

Localization of occult insulin secreting tumors of the pancreas

Percutaneous transhepatic portal venography (PTP) and selective portal blood sample collection for immunoreactive insulin (IRI) analyses was done in four patients who had clinical evidence of the presence of an insulin secreting tumor, but selective arteriogrphy of the pancreas did not visualize any insulinomas. In all patients the clinical diagnosis was confirmed and the localization of the tumors could be calculated with the aid of the PTP and the IRI values detected in different parts of the portal trees. Because no tumor was found at the operation in two patients, despite careful exploration of the pancreas, blind distal pancreatectomy was performed to the point suggested with the help of the investigations, and insulinomas were found close to the resection lines. In the two other patients the proposed localization of the tumor preoperatively was confirmed. There have been no postoperative hypoglycemic symptoms.

Giant insulinoma

A patient with an extremely large insulinoma but short duration of symptoms is reported on. Fasting hypoglycemia, hyperinsulinism, and angiography were the modalities used to diagnose and locate the tumor.

Malignant metastatic insulinoma treated with streptozotocin

A patient with metastatic insulinoma who suffered from severe hypoglycaemic attacks was treated with 7-5 g of streptozotocin (Upjohn). Shortly after the start of treatment, the hypoglycaemic attacks ceased; fasting blood glucose levels and serum immunoreactive insulin values returned to normal upon completion of the treatment. Two years after treatment, the patient is well and active and has not had any attacks. The oral glucose tolerance test and tolbutamide stimulation test now show serum immunoreactive insulin excretion patterns similar to those seen in diabetics.

The surgical treatment of occult insulinomas: a review of the problem

The data from a previously reported large series (1067 cases) of insulin tumours of the pancreas have allowed study of the problem of management of so-called ‚occult’︁ tumours. Of the occult tumours in the whole series, 54 per cent were situated in the head of the pancreas, as opposed to 26.5 per cent similarly located at the initial operation.

Analysis of the records of 542 single benign beta-cell adenomas showed no correlation between the size of the tumour and the duration of symptoms. There were 168 cases of single benign tumours which could not be located at the first operation, but which were cured at a subsequent operation. In 65 per cent of these cases the tumour could not be located at the subsequent operation and was only found after blind resection.

These results indicate that the growth of these tumours is not regular and constant. They lend no support to the suggestion that if an insulin tumour cannot be located blind resection should be avoided in the hope that after 1–2 years, during which symptoms can be controlled by diazoxide, the tumour is likely to he located at a second operation. It is concluded that if the tumour cannot be located the treatment likely to give the best results is progressive blind pancreatic resection from left to right, with careful examination of the excised specimen and frequent estimation of the blood sugar concentration.

Current surgical management of functioning islet cell tumors of the pancreas

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Functioning beta cell tumors (insulinomas) of the pancreas

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Islet cell tumors and hypoglycemia

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