Pancreatic alpha cell tumors: case report and review of the literature

Glucagonoma syndrome

The glucagonoma syndrome is characterized by a necrolytic migratory erythematous rash, angular stomatitis, painful glossitis, a normochromic normocytic anemia, mild diabetes mellitus, weight loss, a tendency to thrombosis, and neuropsychiatric disturbances. The diagnosis is made by finding a high plasma glucagon concentration in the absence of any other cause, such as renal failure or severe stress. A pancreatic alpha-cell tumor can be identified and stained by immunocytochemistry with glucagon antibodies. Optimal treatment is surgical removal, but approximately 50 percent of the tumors have metastasized by the time of diagnosis. Since the tumor is slow-growing, remission can be obtained by hepatic artery embolization to shrink hepatic secondaries or by shrinkage, in about 10 percent of patients, with the combination chemotherapeutic regimen of 5-fluorouracil and streptozotocin. The rash frequently responds to administration of zinc, a high-protein diet, and control of the diabetes with insulin. Alongside the alpha cell in the islets of Langerhans is the D-cell, which produces somatostatin and may well act physiologically as a paracrine inhibitor of glucagon release. A newly developed, long-acting somatostatin analogue, SMS 201-995, which the patient can self-administer as a subcutaneous injection, has proven effective in suppressing glucagon secretion from glucagonomas and, in some cases, causing remission of clinical symptoms.

Effect of streptozotocin in a case of glucagon-secreting malignant islets-cell tumor

A case of a 65-year-old woman with a pancreatic tumor secreting insulin, glucagon, and associated with high PTH levels and hypercalcemia is reported. The patient underwent two Streptozotocin (STZ) treatments (1 g iv/week for 10 weeks) after liver metastases were found. Hormonal and metabolic parameters were monitorized . Before the first STZ treatment insulin levels ranged between 78 and 132 microU/ml. After STZ administration insulin decreased and then remained lower (8-48 microU/ml) until the death of the patient. Pre-treatment glucagon levels ranged between 1.3 and 3.9 ng/ml. STZ induced a decrease of glucagon to 0.5 ng/ml. Glucagon chromatography revealed the prevalence of high molecular weight (greater than 6,000 mol wt) immunoreactive glucagon (0.9 ng/ml) drastically reduced by STZ treatment (0.15 ng/ml). Hypoaminoacidemia was observed before STZ administration, but at the end of the therapy plasma amino acid concentrations were normal. Hypercalcemia too was sensitive to STZ, but not PTH value, which remained high. The second STZ treatment performed a year later was less effective and so a chemotherapeutic protocol was started. Our findings suggest a cytolitic effect of STZ on malignant A-cell, with reduction of glucagon levels and restoration of amino acid metabolism. This effect would be useful for medical treatment of non-operable glucagon secreting tumors.

Glucagonomas. Ultrastructure and immunocytochemistry

Pancreatic tumors harboring glucagon immunoreactive cells were found in four patients with diabetes mellitus. Alpha-cell (glucagon) granules were present in three tumors; pancreatic polypeptide (PP) immunoreactive cells were detected in two. In two patients the tumors were malignant and one of these had the glucagonoma syndrome; the other was a member of a family with MEN-type I syndrome. These cases illustrate three clinical subtypes of glucagonoma.

A light and electron microscopic study on the pancreatic ductal system

To investigate morphological features of the human pancreatic ductal system, light and electron microscopic studies were performed, on the comparative basis with those of several species of mammals. The human pancreas possessed relatively well-developed ductal system, as compared with those of other mammals. Furthermore, it had unique centroacinr cells containing numerous mitochondria. The mode of innervation to the ducts, and cytological features such as cilia formation and mucin production were also revealed. Several kinds of endocrine cells including A, B, D1, ECn, presumptive EC1, and presumptive EC2 or K could be identified, but a few remained unclassifiable. The above findings are considered to be prerequisite for understanding the physiology, especially of bicarbonate production, and pathology, especially of oncogenesis of the exocrine and endocrine pancreas.

Immunohistochemical identification of factor X-like antigen in the A cells of the normal human pancreas

An indirect immunofluorescence technique using two rabbit anti-human factor X sera was used to investigate the presence of factor X in various human tissues. Of all tissues studied only the cytoplasm of some islet cells of the six human pancreases illustrated specific reactivity for factor X-like material. No reaction was seen in the exocrine pancreas. Cross-absorption studies with factor X-deficient plasma, glucagon or alpha-1-antitrypsin did not modify the pattern. On the contrary, cross-absorption with factor X Friuli or with normal plasma eliminated the positivity. No factor X-like material was seen in rat or guinea pig pancreas. The double-immunofluorescence technique demonstrated that the reactivity was localized only in the cytoplasm of the A cells.

Ductuloinsular tumors of the pancreas: a light, electron microscopic and immunohistochemical study

Most pancreatic tumors are of a single cell type and are identified delta as duct, acinar, or islet cell neoplasms. The authors report on three examples with both duct and endocrine characteristics as seen by light microscopy; two with further confirmation of endocrine differentiation by electron microscopy; and one by immunocytochemistry. Mixed differentiation of this sort can be understood by reference to the embryonic pancreas, which develops from the small intestine and forms ducts, intercalated ducts, acini, and islets, with their different cell types. The merging and intermingling of different cell prevents the identification of one specific cell of origin. It also suggests that the neoplastic process here may not be a clonal proliferation from a single cell mutation as this is generally understood. Alternative explanations are briefly mentioned.