Psammomatous somatostatinomas of the duodenum.

The presence of psammoma bodies in carcinoid tumors of the gastrointestinal tract is a rare occurrence; it has also been reported to be associated with features of somatostatin production by the tumor cells. The morphologic features of three such tumors arising in the duodenum were studied by a combination of histochemical, immunocytochemical, and ultrastructural techniques in an effort to delineate their secretory profile and further subclassify them. All tumors showed a mixed architectural pattern with prominent areas of glandular differentiation. The psammoma bodies were almost exclusively located within the glandular lumina. In each instance, the majority of tumor cells showed histochemical and immunocytochemical features of somatostatin-containing cells, and one tumor studied ultrastructurally showed numerous large- and small-sized intracytoplasmic secretory granules, both of which contained somatostatin. In contrast to other endocrine tumors of the duodenum that frequently have a multihormonal secretory profile, psammomatous duodenal carcinoids are associated with the exclusive presence of somatostatin within tumor cells. While many more of such examples of this uncommon tumor need to be systematically investigated for their immunocytochemical and ultrastructural characteristics, duodenal somatostatinomas need to be included in the differential diagnosis of psammomatous tumors.

Ampullary somatostatinoma: psammomatous variant of gastrointestinal carcinoid tumor--an immunohistochemical and ultrastructural study. Report of a case and review of the literature.

A 28-year-old man presented with epigastric pain and obstructive jaundice associated with a histologically and immunologically unusual variant of carcinoid tumor involving the ampulla of Vater. The tumor contained abundant psammoma bodies and exhibited immunoreactivity only for somatostatin. Immunoperoxidase studies for insulin, glucagon, vasoactive intestinal peptide, calcitonin, serotonin, and ACTH had negative results. In contrast to most somatostatinomas of pancreatic origin, clinically this ampullary somatostatinoma was not accompanied by features of the somatostatinoma syndrome. A literature review of the clinical and hormonal features in reported cases of gastrointestinal and pancreatic somatostatinomas is presented.

Exocrine pancreatic insufficiency and pancreatic fibrosis due to duodenal somatostatinoma in a patient with neurofibromatosis.

A case of duodenal somatostatinoma is described in a patient with Von Recklinghausen neurofibromatosis. The patient presented with exocrine pancreatic insufficiency, probably due to distal obstruction of the pancreatic duct by the tumor. Preoperative evaluation with calcium-pentagastrin and tolbutamide stimulation tests were nondiagnostic. At laparotomy, local excision of the tumor was performed. Pathological findings were compatible with duodenal somatostatinoma, causing pancreatic fibrosis. Somatostatin extracted from the tumor coeluted with the somatostatin-14 standard on high performance liquid chromatography (HPLC).

Ampullary somatostatinoma. An immunohistochemical and ultrastructural study.

Two new cases of ampullary somatostatinoma are reported. In one case the tumor is associated with an increase in somatostatin-positive cells in the adjacent duodenal mucosa. Both tumors show a predominant glandular pattern with many psammomatous calcified bodies. Such bodies seem to arise by calcium phosphate encrustation of intraluminal cellular debris. The neoplastic cells contain two distinct types of intermediate filaments: the first is located along the plasma membrane and reacts to keratin antiserum; the other, appearing as paranuclear aggregates, reacts to neurofilament antiserum. The neoplastic cells show signs of intestinal differentiation (microvilli, glycocalyceal bodies, filamentous core rootlets) as well as of neuroendocrine differentiation (secretory granules, whorls of neurofilaments).

Duodenal somatostatinoma with psammoma bodies.

A duodenal somatostatinoma was found incidentally in a 60-year-old woman undergoing cholecystectomy. Microscopically, the tumor had a glandular architecture with abundant psammoma bodies. Electron microscopy revealed tumor cells resembling D-cells of the pancreatic islets. Immunohistochemically, there was staining for neuron-specific enolase, chromogranin, and diffuse cytoplasmic positivity for somatostatin only. By immunoelectron microscopy, somatostatin was identified predominantly in lucent membrane-bound secretory granules. X-ray-dispersive microanalysis showed the psammoma bodies contained calcium apatite crystals. This case is compared with other reported cases with a description of cellular localization of somatostatin and development of psammomatous calcification.

Somatostatinoma: collision with neurofibroma and ultrastructural features.

The clinical presentation, histopathology and immunoelectron microscopic features of two cases of duodenal somatostatinoma are described, one of which is a hitherto unreported example of a collision tumour with a neurofibroma. Ultrastructural morphometric immunoelectron microscopy studies revealed the presence of four types of cells in both tumours, but there was no difference in the proportions of these cells between the collision tumour and the non-collision tumour. Neurosecretory granules ranging in size from 255-815 nm were generally larger than those previously reported for somatostatinomas and somatostatin was identified in granules of all sizes across this range. Neither tumour was associated with the somatostatinoma syndrome comprising associated diabetes mellitis, steatorrhoea and cholelithiasis.

Ultrastructural characteristics of duodenal somatostatinomas. I. Somatostatinoma cells and Schwann-like cells.

This report describes the general ultrastructural characteristics of somatostatinoma cells and Schwann-like cells in two cases of duodenal somatostatinomas. Duodenal somatostatinoma cells had common findings to endodermal cells, i.e. the granules of exocrine type, intracytoplasmic canaliculi, microvilli, small clear vesicles and others. This may suggest that endocrine cells of the gut are of endodermal origin. On the other hand, a few Schwann-like cells were discovered in the tumor nests. Schwann-like cells surrounding the nest of tumor cells were characterized by multilayered piled up cytoplasm, abundant microfilaments and others. This fact suggests that somatostatinoma has some relationship to the nerve.

Ultrastructural characteristics of duodenal somatostatinomas. II. Granules and vesicles.

Ultrastructural findings of granules and vesicles appearing in tumor cells of somatostatinoma are reported. Except for D granules, one granule and four kinds of vesicles were discerned. Some tumor cells had granules of the exocrine type which were similar to those of the chief cells of the stomach. Very small clear vesicles (YO and KO) had accumulated mainly in the apical region of the somatostatinoma cells. Both vesicles were round, unit-membrane bounded and clear in the center, each measuring about 90 and 30 nm in diameter. The cored vesicles normally seen in the sympathetic system were revealed. Doughnut vesicles characterized by double contour membranes were detected together with the cored vesicles. A mixture of exocrine cells of the chief cell-type in the paraneuroma has not been previously reported. And we have as yet very little information as to the doughnut vesicle.

Von Recklinghausen's disease associated with duodenal somatostatinoma: contrast of duodenal versus pancreatic somatostatinomas.

A case of Von Recklinghausen's disease with duodenal somatostatinoma is reported. A search of the world's literature revealed 27 patients with Von Recklinghausen's disease associated with an immunohistologically proved duodenal somatostatinoma. Twenty-nine cases of duodenal somatostatinoma not associated with Von Recklinghausen's disease and 32 cases of pancreatic somatostatinomas have been identified for comparison. While their histology may be similar in many respects, the duodenal and pancreatic somatostatinomas show significant differences, especially in hormonal and growth behaviors. In contrast to its pancreatic counterpart, the duodenal somatostatinoma is frequently associated with Von Recklinghausen's disease, is seldom associated with a recognizable "somatostatin syndrome," often contains psammoma bodies, and is less frequently associated with demonstrable metastases at the time of operation.

Duodenal somatostatinoma. Immunohistopathology and review of literature.

A case of duodenal somatostatinoma is reported. The patient, a 54-year-old male, had complained of an epigastric pain due to gastric ulcer and a duodenal polyp was unexpectedly found at a gastrectomy. The polyp showed basically tubular adenocarcinoma, with negative argyrophil and argentaffin reactions. By an indirect immunofluorescent examination almost all of the tumor cells were revealed as somatostatin-immunoreactive. Big somatostatin was also positive. Radioimmunoassay of the tumor indicated 6400 pg of somatostatin-like immunoreactivity per milligram of wet tissue. This seems to be the second case of duodenal somatostatinoma, following the case reported by us previously.

Somatostatinoma of the cystic duct.

An unusual tumor of the cystic duct in a 28-year-old woman is described. The patient presented with a painful distended gallbladder due to a small tumor occluding the cystic duct. Microscopically the tumor cells showed a nesting pattern suggestive of endocrine differentiation, but contained numerous lipid vacuoles and were argentaffin and argyrophil negative. Ultrastructurally, there were relatively few dense granules measuring 135 to 475 nm. Immunoperoxidase staining showed that the tumor cells contained somatostatin but did not contain immunoreactive ACTH, gastrin, calcitonin, glucagon, insulin, parathyroid hormone, or carcinoembryonic antigen. To the authors' knowledge, this is the first reported somatostatinoma occurring in the extrahepatic biliary tract.

Duodenal somatostatinoma with psammoma bodies: an immunohistochemical and ultrastructural study.

We report a case of malignant somatostatinoma of the ampulla of Vater in a 38-year-old woman with diabetes and cholelithiasis. Immunohistochemistry showed that tumor cells contained only somatostatin and electron microscopy revealed D-type granules in their cytoplasm. Psammoma bodies were numerous and appeared to originate in the cytoplasm of somatostatin producing cells. A review of the literature reveals that somatostatinomas with psammoma bodies are found only in the duodenum and do not produce significant amounts of peptides other than somatostatin.

Amyloid protein in somatostatinoma differs from human islet amyloid polypeptide.

Amyloid deposits in somatostatinomas are rare observations. To examine the characteristics of this amyloid, we compared amyloid deposits in a somatostatinoma to those found in pancreatic tissue in patients with Type II diabetes mellitus and in insulinomas, using immunohistochemical techniques and specific antibodies to islet amyloid polypeptide or other pancreatic hormones, as well as electron-microscopy. Antibodies to islet amyloid polypeptide regions 8-17 or 25-37 were confirmed to be specific. Amyloid deposits in patients with Type II diabetes mellitus and in insulinomas, but not those in the somatostatinoma strongly reacted with these antibodies, or to an antibody to amyloid P component. Amyloid deposits in the somatostatinoma were not reactive with antibodies to somatostatin or to other pancreatic hormones. Electron-microscopic examinations revealed that amyloid fibrils in the somatostatinoma were thinner and more randomly distributed than were those in islets from patients with Type II diabetes mellitus. As amyloid in somatostatinomas is unlike that consisting of islet amyloid polypeptide or other mature pancreatic hormones, it may be a novel type of local amyloid in pancreatic islets.