Human islet cell tumor storing pancreatic polypeptide: a light and electron microscopic study

A 45-year-old man was operated for surgical treatment of a long-standing peptic ulcer disease and upon inspection of the pancreas for suspected Zollinger-Ellison syndrome, tumor nodules were found in this organ. The tumor tissue examined by immunofluorescence showed specific staining only after incubation with anti-pancreatic polypeptide. Negative results were obtained with antisera directed against insulin, pancreatic glucagon, somatostatin, GLI, VIP, secretin, and gastrin. Examination of the tissue by electron microscopy revealed a homogeneous population of small granule-containing cells. This case, therefore, illustrates a tumor composed of one single hormone-producing cell type and allows definition of the ultrastructural features of human pancreatic polypeptide-containing cells.

[A study of pancreatic insulinomas by electron microscopy. 9 cases (author's transl)]

Nine hypoglycaemia-inducing pancreatic tumours were studied by electron microscopy. In 8 of these tumours, it was possible to identify, within the cell cytoplasm, secretory granules with a "paracrystalline" content, identical in appearance to the granules of the B cell of the normal human pancreas. Thus electron microscopy would appear to be a reliable and sensitive method for the morphological identification of these endocrine tumours of the pancreas.

Multinucleated giant cell neoplasm of pancreas: light and electron microscopy features

The morphological features, as demonstrated by electron microscopy, of a rare pancreatic neoplasm indistinguishable from giant cell tumor of bone by light microscopy is presented. These findings are compared with those of the only other case studied by electron microscopy and reported. Features were noted in both studies that are strongly suggestive of the epithelial origin of this neoplasm. However, there were similarities between the material from the current case and giant cell tumor of bone. Degree of differentiation seems to be the most likely determinant of the degree of similarity of the pancreatic neoplasm to the skeletal lesion.

Transplantable pancreatic carcinoma of the rat

Pancreatic carcinoma, which developed in a male Fischer 344 rat fed 0.1% nafenopin for 20 months, is being successfully transplanted into weanling rats. The tumor cells contain variable numbers of zymogen granules, and the endoplasmic reticulum and the Golgi apparatus appear prominent. This transplantable tumor, which displays substantial amylase and lipase activity, should serve as a useful model system for immuno- and chemotherapeutic experiments, as well as for the study of synthesis, storage, and release of zymogen proteins in neoplastic cells.

[Presence of "pancreatic polypeptide" cells, and gastrin immunoreactivity in immuno-induced exocrine pancreas carcinoma]

1) In electively immuno-induced carcinomas of the exocrine pancrease in Mice, where A (glucagon) and B (insulin) endocrine cells persist, cells with a pancreatic polypeptide immunoreactivity are also detected, even in late evolution stages. These cells, like D cells, containing somatostatin, are localized only in the pancreatic remains surrounding the anaplasic carcinomatous tissue: islets, adenomatous parenchyma, and ductular epithelium. Ultrastructure of these cells shows their active elaboration of numerous chracteristic secretion granules. (2) Immunocytoenzymatic detection of gastrin is negative in the exocrine and endocrine pancreatic tissues. However one of the anti-gastrin sera used gives a positive reaction, in some carinomatous cells only. Does this immunoreactivity characterize a polypeptide specific to the pancreatic carcinomatous cell?

Nesidioblastosis: the pathologic basis of persistent hyperinsulinemic hypoglycemia in infants. Morphologic and quantitative analysis of seven cases based on specific immunostaining and electron microscopy

Seven surgical specimens of pancreas, obtained at laparotomy from infants suffering from persistent hyperinsulinemic hypoglycemia, were analyzed by qualitative and quantitative immunocytochemistry and by electron microscopy. In five cases a multifocal ductuloinsular proliferation, in one a focal adenomatosis, and in one a solitary encapsulated nodule (adenoma) were observed. Combinations of the different patterns of proliferation were seen in six cases. Budding off from the ductular epithelium and interposition of endocrine cells between ductular epithelial cells were prominent features common to all cases. An almost fivefold increase of the mean total area occupied by endocrine tissue was found over that of age-matched controls. Four cell types were seen to participate regularly in the proliferation, and their ratios were remarkably constant in all cases, mean figures being 62:21:9:8% for B:A:D:D1 cells, respectively. The ratio of B cells per total endocrine area in nesidioblastosis was very close to that per islet of the controls (62:59%). Since common features were found in all or in the majority of cases, it is suggested that the various patterns of proliferation are merely morphologic variations of the same basic defect. Nesidioblastosis may result from inappropriately controlled development of the endocrine pancreas that is not arrested but carries on beyond birth and during infancy. The application of specific immunocytochemistry as a necessity for full appreciation of the extent of endocrine proliferation is stressed.

[Persistance of endocrine cells in immuno-induced carcinoma of the exocrine pancreas: insulin, glucagon, and somatostatin cells]

In immuno-induced exocrine pancreatic carcinomas, which keep their exocrine secretory specificity through their different evolution stages [(1), (2)], normal B, A and D endocrine cells are still found, demonstrated by immunochemical techniques. They are localized in the islets of Langerhans. B and A cells are scattered in adenomatous pancreatic remains, and in the anaplasic carcinoma; D cells are found in the ductular and adenomatous remains. The three types of endocrine secretion granules are analyzed by electron microscopy at the early and late stages of carcinogenesis. The origin of the persisting endocrine cells and the nature of undifferentiated cells proliferating from the ductular epithelium are discussed.

Cystadenoma of the pancreas. An ultrastructural study

A case of cystadenoma of the pancreas was studied at the light (LM) and the ultrastructural (EM) levels. The observation made under LM that the flattened epithelial cells lining the cystic spaces were similar to the centroacinar cells of a normal pancreas was supported by EM findings. Numerous glycogen granules were demonstrated in the cells, a feature characteristic of fetal but not adult centroacinar cells. A few epithelial cells contained occasional membrane bound dense granules of unknown nature. This observation and the finding of normally appearing islets of Langerhans raise the possibility that this may be an example of a mixed insular-duct cystadenoma. However, if the islets of Langerhans were considered entrapped structures, this tumor should be labelled as a simple serous cystadenoma.

"Somatostatinoma": a somatostatin-containing tumor of the endocrine pancreas

We studied the pancreatic and enteric hormone profile of a 46-year-old woman who had hyperglycemia and a pancreatic tumor. Before operation, there was no evidence of overproduction of glucagon or insulin. The tumor's ultrastructure had a distinctive endocrine morphology, resembling D cells. Prompted by the recent demonstration of somatostatin in D cells of pancreatic islets, we analyzed the tumor and found a large quantity of immunoreactive somatostatin (301 ng per milligram of tissue). Insulin, glucagon, gastrin, vasoactive intestinal polypeptide and human pancreatic polypeptide were present in only trace quantities. The tumor cells were cultured in monolayers, which remained viable up to 51 days and released somatostatin into the culture medium. In seven insulinomas and two glucagonomas, we found the somatostatin content either much lower (less than 0.6 ng per milligram of tissue) or undetectable. After complete resection of the tumor, our patient became euglycemic and has remained so for the past 20 months.

Pancreatic somatostatinoma. Clinical features and physiological implications

The first case of a tumour producing somatostatin-like immunoreactivity and bioactivity is presented. The pancreatic tumour was composed of cells indistinguishable from islet D cells. Radioimmunoassay of blood-samples obtained by tumour-vein catheterisation revealed very high levels of somatostatin immunoreactivity. On gel chromatography tumour extracts were found to contain at least 4 different immunoreactive components, one of which eluted in the position of synthetic somatostatin. Extracts from the tumour were potent in inhibiting insulin and glucagon secretion from isolated perfused porcine pancreas. Clinical abnormalities included hypochlorhydria, steatorrhoea, and diabetic glucose tolerance. Conceivably some of these abnormalities may be related to somatostatin hypersecretion from the pancreatic tumour.

Immunohistological study on the ACTH producing islet cell carcinoma of the pancreas

ACTH producing cells in islet cell carcinoma associated with Cushing's syndrome were studied by an improved immunoperoxidase as well as immunofluorescence technique. The cells which contained ACTH antigen were distributed throughout the tumor tissue of both primary and metastatic lesions in rather small numbers. In the small cancer nests they were present in an irregular or mosaic pattern and, on the contrary, they tend to line along the margin in the larger nests. The intracytoplasmic localization of the ACTH antigen was characteristically demonstrated in the infranuclear area of the tumor cells, closely simulating that of the argentaffin granules of the enterochromaffin cells. The electron microscopic observation identified membrane enclosed, cored granules, 200-300 nm in diameter, present in clusters in the infranuclear area of some tumor cells, which were considered corresponding well to the ACTH positive cells in immune staining.

Carcinogenesis in the pancreas. I. Long-term explant culture of human and bovine pancreatic ducts

Bovine and human pancreatic ductal explants were maintained in long-term culture. Bovine ducts were cultured for 85 days, whereas human ducts have been cultured for up to 60 days. The explants all maintained good ultrastructural preservation for these periods and also incorporated radioactive precursors into protein, RNA, and DNA. Uncultured ducts, which were fixed for electron micrsoscopic study, demonstrated classical signs of reversible cell injury (dilated endoplasmic reticulum and swollen mitochondria), and cultured explants did not. However, the cultured tissues did show sublethal alterations such as the formation of numerous autophagic vacuoles and residual bodies and the accumulation of large lipid droplets. This study demonstrated the feasibility of maintaining pancreatic ducts in long-term explant culture, which enables them to be used in experimental studies involving chemical carcinogens and in structural and functional studies.

Acinar cell neoplasms of the exocrine pancreas

The pathological features of 12 acinar cell neoplasms of the pancreas are described; these comprise 11 carcinomas, of which seven were pure acinar cell growths and four were mixed acinar and ductal carcinomas, and one adenoma. These tumors occurred in a series of 105 during the period 162-75. Thrombotic endocarditis developed in three out the 11 carcinoma cases. The distinctive histological features of these neoplasms and the means of differentiating them from anaplastic carcinomas and certain other carcinomas, for example, islet cell carcinoma, oat cell carcinomas, and carcinoid tumours, are discussed. The poor prognosis of pancreatic cancers is emphasized, and reasons are put forward for believing that future epidemiological studies may need to take account of the histological types of pancreatic carcinoma.

Establishment and characteristics of a human pancreatic cancer cell line (HCG-25)

A floating cell line (HCG-25) was established from the metastatic ascitic fluid of a human pancreatic adenocarcinoma of ductal cell origin. The cell line was characterized by the growth in suspension with a doubling time of 15.6 hr, a high cloning efficiency in soft agar and a modal chromosome number of 72. Electron microscopic examination revealed terminal bars in a small number of cells. Production of mucin and immunoglobulins and phagocytosis were not demonstrated. Heterotransplantation of the cells produced tumors, being undifferentiated carcinoma histologically. These characteristics mentioned above confirm that HGC-25 cell line is a human pancreatic cancer cell line.

Streptozocin-treated Verner-Morrison Syndrome: plasma vasoactive intestinal peptide and tumor responses

A patient with watery diarrhea, hypokalemia, hypochlorhydria, and a non-beta islet cell carcinoma of the pancreas (Verner-Morrison syndrome) was found to have an elevated vasoactive intestinal peptide (VIP) concentration in the plasma as well as in the tumor. Treatment with streptozocin resulted in a dramatic subjective and objective tumor response in this patient. Plasma VIP concentration fell into the normal range after four courses of treatment, diarrhea ceased after the third course of therapy, and measurable tumor mass markedly decreased during that same period of time. The patient remains in clinical remission with no evidence of tumor regrowth 18 months after the beginning of treatment. In this patient, plasma VIP measurements were an excellent marker of tumor activity and correlated well with objective disease measurements and clinical response.

A highly differentiated exocrine pancreatic tumour in a young boy

A primary pancreatic tumour in a 6-year-old boy was removed by radical excision. From both light and electron microscopic observations the tumour was considered to be of exocrine origin, with some differentiation towards acinar cells. Although the tumour was highly differentiated, it was regarded as probably malignant because of tumour growth into the surrounding fibrous capsule. The case is discussed in relation to earlier rare reports of pancreatic tumours in infants and children.

Insulin secretion by human pancreas cultured for one year

The pancreas of a child with intractable neonatal hypoglycemia was explanted in tissue culture on plasma clot and in monolayer culture after enzymatic dissociation. 1. Cytological and immunoenzymatic studies of pancreas before explantation showed a very altered structure, suggesting a polyendocrine tumor composed mainly of B cells. Endocrine cells were present in the epithelium of duct-like structures. Large islets were often in continuity with these structures, suggesting islet budding from ducts, and supporting the hypothesis of the persistence of embryonic characteristics. 2. In vitro, the pancreatic endocrine cells survived and proliferated; they were maintained for 362 days. During this time, they maintained their secretory capacity, as shown by radioimmunoassays of the culture media: the cells released insulin in rapidly decreasing amounts, then continued excreting low levels (5 to 60 muU/flask/day), in alternative periods of secretion and absence of secretion. 3. Cytological study by light and electron microscopy of the cells in tissue and in monolayer cultures shows that they can undergo morphological changes, and may become epithelioid, fibroblastoid or round, while retaining their secreting activity. 4. In long-term culture, the cells did not contain typical mature secretion granules. The hormone might be released into the medium by a clasmatosis mechanism. On the other hand, hormone excretion by vesicles originating from the rough endoplasmic reticulum is possible.

Pancreatic carcinoma in infancy. An electron microscopic study

A case of a malignant epithelial tumor of tail of the pancreas in a 3-year-old Japanese girl is presented. This is the fourth case reported with ultrastructural study. This type of pancreatic carcinoma of the infant has no endocrine granules or endocrine function. The ultrastructural study suggests that the tumor is derived from a primitive epithelial cell with differentiation toward acinar cell.

Fine structure of pancreatic adenocarcinoma induced in rats by 7,12-dimethylbenz(a)anthracene

We induced pancreatic adenocarcinomas in Long-Evans rats by placing crystals, 2-3 mg, of 7,12-dimethylbenz[a]anthracene (DMBA) in a 2- to 3-mm incision in the "head" of the pancreas approximately 1 cm from the duodenum. The incisions were closed with one or two silk sutures. The animals were killed 4-10 months after DMBA implantation, and nodules were removed and routinely prepared for light and/or electron microscopic study. Histologic organization varied from normal, through areas of tubule-like structures, to sheets of pleomorphic tumor cells. Electron microscopic study of tumor cells revealed large electron-lucent nuclei that frequently had irregular outlines and prominent nucleoli. The predominant feature of the cytoplasm was abundant rough endoplasmic reticulum. Zymogen granules were rare. Adjacent cells sometimes were jointed by an apical junctional complex to form a lumen into which projected irregular microvilli. A basal lamina sometimes occurred at the bases of the tumor cells. The fine structural similarity of these tumor cells to acinar cells was noted.

Electron microscopy in the cytological examination of metastatic pleural effusions

In a previous publication the ultrastructure of pleural effusions in cases of pleural mesothelioma was reported. The same method has now been applied to a study of effusions produced by pleural metastases. The findings are considered sufficiently conclusive to justify the use of electron microscopic cytology in determining the nature and sometimes the origin of such effusions.

Spontaneous Pancreatic beta cell tumor in the rat. A light and electron microscopic study

Fine structural study of a pancreatic neoplasm found at autopsy of a 27-month-old female Long-Evans rat showed that the tumor consisted of, and derived from beta cells of the islets of Langerhans.