Cystadenoma of the pancreas. An ultrastructural study

Solid serous adenoma of the pancreas. The solid variant of serous cystadenoma?

Serous cystadenomas of the pancreas are uncommon benign neoplasms that occur most frequently in elderly females. Characteristically, the tumors have a spongy gross appearance and are composed of innumerable cysts lined by flat, cuboidal, and polygonal cells with clear to pale eosinophilic cytoplasm and round, hyperchromatic central nuclei. Macrocystic variants with an oligolocular gross appearance have also been described. In this report we describe a solid pancreatic neoplasm arising in a 70-year-old woman who remains well 5 years after a distal pancreatectomy. The well-circumscribed tumor measured 4.0 cm in maximal diameter and was formed by clear to pale polygonal to cuboidal cells arranged in nests, sheets, and trabeculae separated by thick fibrous bands. Although small acini with glandular spaces were present within the nests, cystic spaces were absent. Periodic acid-Schiff (PAS) and PAS-dismutase (PAS-D) stains revealed a large amount of cytoplasmic glycogen. The tumor cells were immunoreactive for CAM 5.2, epithelial membrane antigen, and neuron-specific enolase. The cytologic, histochemical, and immunohistochemical features of the tumor were indistinguishable from those of serous cystadenomas; therefore, we believe this solid serous adenoma represents a solid variant of serous cystadenoma. Recognition of this lesion is important because the vast majority of solid tumors in the pancreas are malignant. The differential diagnosis includes the rare primary clear-cell "sugar" tumor of the pancreas, clear cell carcinoma, clear cell islet cell tumor, and metastatic renal cell carcinoma.

Serous oligocystic and ill-demarcated adenoma of the pancreas: a variant of serous cystic adenoma

Serous cystic tumours of the pancreas are uncommon and are usually classified as microcystic adenomas (MCA). As new types of serous cystic tumours of this organ have been reported we reviewed a series of 14 lesions and from macroscopic findings two groups were distinguished: ten tumours revealed the features of MCA, while four were clearly distinct from MCA. Grossly, the latter tumours showed only few cysts which were irregularly assembled in fibrous stroma. On the cut surface, there was neither a central stellate scar nor a circumscribed tumour border, features characterizing MCA. Microscopically, the cysts were lined by cuboidal, non-mucin-producing cells. Immunocytochemical staining for cytokeratins 7, 8, 18 and 19 revealed a ductal phenotype. All non-MCA were found in the head of the pancreas and three of them occurred in men. There were no tumour recurrences or signs or malignant transformation after resection (mean follow-up, 2.9 years). These results suggest that there are serous cystic tumours distinct from MCA which may represent another variant of the category of serous cystic adenomas of the pancreas. We propose the term serous oligocystic and ill-demarcated adenoma (SOIA) for these tumours. It is possible that the recently described macrocystic sybtype of serous cystadenoma and SOIA and variants of the same tumour.

A rare case of serous cystadenocarcinoma of the pancreas

Serous cystadenocarcinoma of the pancreas, a rare disease, developed in a 63-year-old Japanese woman. Pathologic examinations of the pancreatic tumor at the subtotal pancreatectomy showed it to be serous cystadenoma with focal atypical lesions. Three years after the operation, however, metastatic liver nodules were found, and the histologic characteristics of these lesions were quite similar to those of the pancreatic neoplasm. Both primary and metastatic tumors were composed of multiple cysts separated by fibrous septa. The epithelium of cysts was cuboidal and had clear cytoplasm, which had positive results for periodic acid-Schiff (PAS) and negative results for PAS with diastase, Alcian blue, and mucicarmine. To the knowledge of the authors, serous cystic neoplasms of the pancreas have been uniformly benign in biologic behavior. Recently, however, serous cystadenocarcinoma of the pancreas has been reported as a new entity. The current case is the second reported case and might support the existence of serous cystadenocarcinoma of the pancreas.

Some considerations on the biology of pancreatic serous cystadenoma

Five cases of pancreatic serous cystadenoma were examined pathologically, and their nuclear DNA ploidy patterns were determined. Four were unifocal tumors, and one was a multifocal tumor. The four unifocal tumors were typical serous cystadenomas. However, the multifocal tumor exhibited an increased N/C ratio, irregular nuclear margins, various-sized nuclei, coarse nuclear chromatin, and neural invasion. All tumor cells were stained with antiCA19-9 but none with antiCEA. In the antiCA19-9 staining, the four unifocal tumors and the tumors of the pancreatic tail in the multifocal case were positive only on the apical membrane, whereas the tumor cells of the pancreatic head in the multifocal case were positive within the whole cytosol. The unifocal tumors were diploid with a DNA Index (DI) of 1.0 and proliferation indices (PI) from 4.9 to 20.9% with a mean of 14.4%. In the multifocal case, the tumor in the pancreatic head was aneuploid (DI = 1.9) and had a PI of 27.8%. The multifocal sites in the pancreatic body were aneuploid (DI = 1.9) with a PI of 22.4%. We suggest that the biological property of serous cystadenoma should be revisited.

Multifocal pancreatic serous cystadenoma with atypical cells and focal perineural invasion

A case of multifocal pancreatic serous cystadenoma with atypical cells is reported. The patient was a 72-yr-old female who complained of jaundice. The distal common bile duct was obstructed, and the proximal bile duct was remarkably dilated on cholangiography. The main portal vein was obstructed and collateral vessels had developed on portal angiography. Total pancreatectomy was performed. The resected specimen contained one tumor in the head of the pancreas, five in the body, and one in the tail. The tumors of the head and body were morphologically the same. Microscopically, both contained spongelike multilocular cysts on their cut surfaces. These cysts were covered with low cuboid epithelium containing clear cytoplasm and abundant glycogen. Neural invasion was also found. The tumor cells exhibited an increased N/C ratio, variable nuclear size, irregular nuclear margins, and coarse nuclear chromatin. These tumors had aneuploid nuclear DNA with a DNA index of 1.9 and a proliferation index of 0.28. We feel that it is necessary to reconsider the biological concept of serous cystadenoma.

Virus-induced pancreatic cancer in guinea fowl. An electron-microscopical study

Pancreatic tumors were induced in guinea fowls inoculated with virus strain Pts-56. Sequential high-resolution light microscopic and ultrastructural studies revealed consecutive occurrence of alterations in the pancreas of the infected birds. From the second month p.i., there were nonobligatory, unspecific focal degenerative changes in acinar units that were replaced by tubular complexes, lined with centroacinar-like cells. From the third month, proliferation of ductule structures with mucin-producing or mucin-nonproducing epithelium occurred, giving rise to cystic and papillary adenomas. From the fourth to sixth months, pancreatic adenocarcinomas and poorly differentiated carcinomas arose. The cells of the serous adenomas ultrastructurally resembled the normal pancreatic centroacinar and ductular cells with their regular glandular arrangement on basal lamina, elongated nuclei with finely dispersed heterochromatin, scanty cytoplasmic organelles, microvilli, and occasional cilium. The cells of the mucinous tumors showed similarities to ductal cells with their darker cytoplasmic matrix, larger number of small mitochondria, microfilaments, vesicles, mucin granules, and extensive interdigitations. The cells of the pancreatic carcinomas revealed irregularities in glandular formation, nuclear polymorphism, low cytodifferentiation, and ultrastructural abnormalities, but in most cases retained basic fine structural similarities to the epithelium of the pancreatic ductal system. The present results indicate that the centroacinar cell is the cell of origin of the broad spectrum of pancreatic neoplasms with various differentiation and malignancy induced in guinea fowl by virus strain Pts-56.

Mucinous cystic tumour of the pancreas. A histological and histochemical study

A histological and histochemical analysis of two new cases of mucinous cystic tumors of the pancreas is reported. Histochemical study revealed a predominantly sulphated acidic mucin secretion with some neutral mucins. Argyrophilic elements were also observed. The authors propose an origin from intestinal type epithelium through a metaplastic process.

Pancreatic cystadenoma in an infant: ultrastructural study

A 10 x 6 x 4 cm multicystic cystadenoma arose in the pancreas of a 4-month-old male. Microscopically, the cysts were lined by short columnar or cuboidal cells that contained neither mucin nor glycogen. The lining cells had occasional nucleoli, contained electron dense vacuoles and apical aggregates of filaments, and were associated with a basal lamina. This is the youngest patient reported as having pancreatic cystadenoma, and the ultrastructure of the neoplasm was different from the 6 previously studied adult cases, suggesting that infantile and adult cystadenomas are different in nature.

Cystic neoplasms of the pancreas

Cystic neoplasms of the pancreas, including 4 patients with serous cystadenoma and 11 with mucinous cystic neoplasm, were studied. Serous cystadenomas composed of epithelial cells with glycogen in the cytoplasm were benign in all, whereas mucinous cystic neoplasms consisted of four benign, two borderline, and five malignant lesions. The average size was 1.8 cm in the greatest diameter in benign mucinous cystadenomas, about 5 cm in borderline tumors, and more than 8 cm in mucinous cystadenocarcinomas. Histologically, in all borderline and malignant lesions, the cysts contained areas lined with epithelium and had a benign appearance, comparable with that of mucinous cystadenoma. These observations suggest a borderline or malignant disease in the case of a benign mucinous cystadenoma. An immunohistochemical study for carcinoembryonic antigen and carbohydrate antigen 19-9 showed denser and diffuse localizations of such materials in the cytoplasm and the stroma in the case of malignant lesions, as compared to findings in borderline and benign cases.

Acinar cell cystadenocarcinoma of human pancreas

A 7000 g cystic tumor replacing the body and tail of the pancreas was resected in a 64-year-old man. Numerous peritoneal implants confirmed its malignant nature. Light microscopy of both the primary tumor and the implants revealed distinctive cytoplasmic eosinophilia and apical granules. Ultrastructural examination demonstrated numerous zymogen granules and abundant, rough endoplasmic reticulum, which confirmed that the tumor was composed of acinar cells. No mucinous or serous differentiation was detected. We have not found report of a similar tumor.

Cystadenoma of the pancreas: a histological, histochemical and ultrastructural study of seven cases

Seven cases of cystadenoma of the pancreas were examined in detail histologically and histochemically and two variants were identified: a microcyst type lined by glycogen-rich cuboidal epithelium which also secretes some neutral mucins; and macrocystic type lined exclusively by mucus-secreting columnar cells which secrete predominantly sulphated acidic mucins with some neutral mucins. Electron microscopy of two cases of the microcystic variant showed neoplastic cells with an ultrastructure comparable to that of centroacinar cells of the normal exocrine pancreas.

Ductular origin of pancreatic cancer and its multiplicity in man comparable to experimentally induced tumors. A preliminary study

The histologic features of 3 randomly selected pancreatic cancer cases are compared with those found in Syrian hamsters after treatment with N-nitrosobis(2-oxopropyl)amine (BOP). The 3 human cases all exhibited hyperplastic, preneoplastic and malignant changes which were markedly multicentric, and which arose predominantly from ductules, as well as from small ducts. The findings were comparable to those in the hamster mode. Proliferation and malignant alterations of the intrainsular ductules were commonly seen in both human and experimental tumors. The data is consistent with the concept that cells of the small ducts and especially of the ductules represent a potential source of human, as well as experimental, tumors. The small number of human cases studied does not allow generalization, but the marked resemblances in all 3 randomly selected pancreatic cancer cases were remarkable.