Functioning beta cell tumors (insulinomas) of the pancreas

Anatomic distribution of pancreatic endocrine tumors

Pancreatic endocrine tumors are grouped together by their common histologic, cytochemical, and ultrastructural features. Although useful conceptually, this paradigm has been unable to predict the anatomic location of different tumor types. Successful surgical excision of these tumors would be facilitated by an improved understanding of their anatomic distribution. Based on the available data, a bimodal distribution of pancreatic endocrine tumors was identified. Cluster 1 (gastrinomas, pancreatic polypeptide (PP)-secreting tumors, somatostatinomas) had 75% of tumors to the right of the superior mesenteric artery, whereas cluster 2 (insulinoma, glucagonoma) had 75% of tumors to the left of the superior mesenteric artery (p less than 0.05). This distribution is similar to that distribution predicted based on the volume density of the corresponding islet cells for insulinoma, glucagonoma, and PP-secreting tumors, but not for somatostatinoma. These findings suggest that pancreatic endocrine tumors are derived from similar cytologic precursors as pancreatic islet cells, and their distribution may be a consequence of embryologic development from either the ventral (cluster 1) or dorsal (cluster 2) pancreatic buds.

A patient with insulinoma presenting for psychiatric assessment

A case of insulinoma referred for psychiatric assessment illustrates the need for a high index of suspicion of organic mental disorder even in patients who have undergone previous extensive medical investigation. The diagnostic difficulties illustrate the need for persistence and cooperation between specialists in such cases.

Neurological aspects of insulinomas

Neurological involvement occurred in every one of a series of 30 patients with an insulinoma. The episodic nature of the hypoglycaemia caused symptoms and signs to fluctuate and often led to delay in diagnosis (mean length of history was 3 years). The commonest feature at first presentation was confusion (20 instances), but as the illness evolved, coma (16 instances) and convulsions (8 instances) became more frequent. Objective weakness was found in 7 patients, with 3 examples of hemiparesis and 2 each of paraparesis and monoparesis; in all, the weakness resolved over a period of 1 hr to 3 days when normoglycaemia was maintained. Other neurological features included subjective visual disturbances, headache, dysarthria and ataxia. 220 patients with an insulinoma from 7 series in the literature were reviewed. The high incidence of neurological features was confirmed, with confusion (152 cases), coma (82 cases) and convulsions (58 cases) predominating. Visual disturbances were common, though not accurately quantified in some series. Objective evidence of weakness on the other hand was reported in only 6 of the 222 patients. Other less common symptoms included headache (18 instances) and peripheral paraesthesiae (14 instances). In the 7 series reviewed, as in our own, it was found that in any one patient, each episode of hypoglycaemia was accompanied by the same symptom complex. The presence of an insulinoma should be considered in any patient with unusual, or inexplicable neurological features, particularly when they are intermittent. The diagnosis can be confirmed by demonstrating an inappropriately high circulating insulin level, for the ambient blood glucose concentration.

Pancreatic nesidioblastosis in adults. Report of a patient with hyperinsulinemic hypoglycemia

Hyperinsulinemic hypoglycemia in neonates occurs most commonly secondary to nesidioblastosis, a persistence of fetal development of the endocrine cells of the pancreas. In adults, hyperinsulinemic hypoglycemia is usually due to insulinoma or beta-cell hyperplasia. Nesidioblastosis arising in adults has only recently been reported. An adult patient with nesidioblastosis has been described. The light and electron microscopic films of this entity are shown in detail, and the embryology and treatment are discussed. Further understanding of this newly described disease entity will require research on factors that regulate the differentiation of beta cells of the pancreas.

Insulinomas in Northern Ireland between 1960 and 1980. A review of 16 cases

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Insulinoma: diagnosis, surgical management and long-term follow-up. Review of 41 cases

The clinical features, diagnosis and surgical considerations in 41 patients with insulinoma treated at Columbia-Presbyterian Medical Center are presented along with a review of the literature. One hundred percent of patients surviving surgery for benign functional beta cell tumors were cured of hypoglycemia. A detailed long-term follow-up study in the majority of patients after surgical cure documented a statistically significant incidence of neuropsychiatric aberration, adult-onset diabetes mellitus and peptic ulcer disease. Patients who have undergone surgery for endogenous hyperinsulinism should be followed up carefully for the development of these disorders, and their overall prognosis should be considered cautiously.

An insulinoma presenting with reactive hypoglycaemia

A 57-year-old woman presented with symptoms which were cured by the removal of an insulinoma. The case was atypical in that symptomatic hypoglycaemia occurred only after meals or glucose administration but never during fasting, and thus if plasma insulin activity had not been measured an incorrect diagnosis of reactive hypoglycaemia might have been made on the basis of symptoms and oral glucose-tolerance test. Reactive hypoglycaemia resulted from an increased rate of glucose assimilation and possibly also from a decreased rate of gluconeogenesis due to the immense insulin secretion provoked by glucose or food. The findings suggest that a diagnosis of hypoglycaemia should not be made until the possibility of an insulinoma has been excluded by measurement of plasma insulin activity during a period of hypoglycaemia.

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.