Combined DOG1 and Mammaglobin Immunohistochemistry Is Comparable to ETV6-breakapart Analysis for Differentiating Between Papillary Cystic Variants of Acinic Cell Carcinoma and Mammary Analogue Secretory Carcinoma

BACKGROUND

We investigated the reliability of combined DOG1 and mammaglobin immunohistochemistry compared with ETV6 fluorescence in situ hybridization (FISH) in the assessment of salivary tumors previously diagnosed as acinic cell carcinoma (ACC). Ultrastructural features of cases reclassified as mammary analogue secretory carcinoma (MASC) were assessed by transmission electron microscopy (TEM).

METHODS

Immunohistochemical (IHC) reactivity to DOG1 and mammaglobin was validated against FISH targeting the ETV6 gene in all 14 cases.

RESULTS

Three cases with papillary cystic histomorphology previously diagnosed as ACC were revised to MASC. TEM features of the ETV6 rearrangement-positive MASC cases showed large numbers of secretory granules with extrusion into the intercellular spaces, well-developed endoplasmic reticulum, lipid-laden vacuoles, well-formed microvilli, and large lining cystic spaces.

CONCLUSIONS

Combined DOG1 and mammaglobin immunohistochemistry is comparable to ETV6 -breakapart analysis for differentiating between papillary cystic variants of ACC and MASC.

Pancreatic-type Acinar Cell Carcinoma of the Stomach Included in Multiple Primary Carcinomas

BACKGROUND/AIM

Pancreatic-type acinar cell carcinoma (ACC) in the stomach is extraordinarily rare. We pathologically examined two cases with multiple primary carcinomas, including gastric tumors.

PATIENTS AND METHODS

Gastric cancer specimens were examined by immunostaining and electron microscopy.

RESULTS

Both cases had cancer cells with acinar patterns, resembling pancreatic ACC. The cancer cells in the first case were positive for exocrine markers, including chymotrypsin, lipase and alpha-1 antichymotrypsin (ACT), as well as neuroendocrine markers, including chromogranin A and synaptophysin. The cancer cells in the second case were positive for chymotrypsin and alpha-1 ACT, while being slightly positive for chromogranin A and synaptophysin. Ultrastructurally, cancer cells contained zymogen granules in both cases. The final diagnosis was pancreatic mixed acinar-neuroendocrine carcinoma and pure pancreatic ACC, respectively.

CONCLUSION

We confirmed two cases with gastric pancreatic-type ACC included in multiple primary carcinomas. This type of double cancer has not been reported previously.

Fine-needle aspiration cytology of pancreatoblastoma in a young woman: report of a case and review of the literature

Pancreatoblastoma is a rare tumor and has been reported only four times in the cytologic literature, three times in fine-needle aspiration (FNA) biopsy and once in an imprint of resected tumor. We are reporting the fourth case of FNA cytology with immunohistochemical and electron microscopic studies. The patient is a 24-yr-old African American woman, who presented with a pancreatic mass, hepatic masses, and abdominal lymphadenopathy. The aspiration smears of the liver mass showed a biphasic tumor composed of bland-appearing primitive spindled stromal fragments with "spider-web"-like long fibrils interconnecting with sharply angulated islands of cohesive epithelium. At high power, the epithelium is composed of medium-sized cells with round-to-oval vesicular nuclei with fine chromatin and one-to-two small nucleoli. The neuroendocrine component was demonstrated immunohistochemically with synaptophysin and chromogranin expressions. The acinar component and squamoid component were demonstrated ultrastructurally by the presence of 400-600 nm zymogen granules and tonofilaments. The literature was reviewed and the cytological features of all the four cases of pancreatoblastoma are summarized.

Sinonasal acinic cell carcinoma: a clinicopathologic study of four cases

BACKGROUND

Acinic cell carcinoma is a low-grade malignant epithelial salivary gland neoplasm with a predilection for the parotid gland. To date, only 11 cases of sinonasal acinic cell carcinomas have been reported in the English-language literature. We present the clinicopathologic features of four sinonasal acinic cell carcinomas.

METHODS

The demographic data and pathologic material of four patients with sinonasal acinic cell carcinoma identified from the files of the Department of Pathology at The University of Texas M. D. Anderson Cancer Center between 1984 and 2002 were reviewed.

RESULTS

The four patients were two men and two women, with an age range of 42 to 65 years (mean, 54 years). The patients were initially seen with unilateral nasal obstruction. Histologically, all tumors were composed of round to ovoid cells with clear and/or basophilic granular cytoplasm and round, hyperchromatic, small, eccentrically located nuclei. The growth pattern was lobular, solid, and follicular. Histochemically, periodic acid-Schiff diastase-resistant granules were demonstrated in all cases. All patients were treated surgically. In addition, one patient received postoperative radiation. All patients are alive and well, with follow-up from 4 to 17 years.

CONCLUSIONS

Sinonasal acinic cell carcinoma is a distinct low-grade carcinoma that can be distinguished from other neoplasms by light microscopy and histochemical staining methods. Pathologists and surgeons should be aware of the occurrence of this type of salivary gland neoplasm in the sinonasal tract.

Pancreatic acinar cell carcinoma with endocrine differentiation: immunohistochemical and ultrastructural analyses

The majority of pancreatic malignant tumors are adenocarcinomas of the ductal type (ductal cell carcinomas) and combined tumors consisting of different tumor components are very rare. We present here a rare case of acinar cell carcinoma with apparent foci of endocrine differentiation. A 46-year-old man underwent pylorus-preserving pancreatoduodenectomy under the diagnosis of pancreatic tumor. The pancreatic tumor was mainly composed of typical acinar cell carcinoma, but some tumor cells were positive for both acinar and endocrine cell markers such as pancreatic amylase, trypsin, lipase and chromogranin A. At the electron-microscopic level, the tumor cells were seen to have numerous electron-dense neuroendocrine, as well as a few zymogen-like, granules. The tumor part positive for both acinar and endocrine cell markers originated from a subclone (dis-differentiated tumor cells) of the typical acinar cell carcinoma tissue of the pancreas.

Acinar cell carcinoma of the pancreas showing finger-print-like zymogen granules by electron microscopy: immunohistochemical study

A rare case of finger-print-like zymogen granules shown by electron microscopy is reported. The patient was a 75-year-old man who was histologically and ultrastructurally confirmed to have acinar cell carcinoma of the pancreas. Frozen section and postmortem examination revealed that the tumor was made up of solid nests of cells resembling the appearance of normal pancreatic acini, showing polygonal cells which had round or oval nuclei, and rare mitotic figures. Zymogen-like granules, shown by eosinophilic granular staining, were abundant in the cytoplasm. Electron microscopy showed that the tumor cells were closely packed, occasionally forming small intercellular spaces resembling pancreatic acini (microtubules). The cytoplasm contained characteristic zymogen granules with dark-to-medium electron density, measuring 660 nm +/-213 SD in diameter. The granules of medium density were large, and showed finger-print-like patterns. Investigation of more cases is necessary to identify whether these finger-print-like patterns are an important factor in the genesis of acinar cell carcinoma.

Immunohistochemistry in the differential diagnosis of acinar and endocrine pancreatic neoplasms

Histologic differential diagnosis of acinar cell carcinoma (ACC), mixed acinar-endocrine cell carcinoma (MAEC), and pancreatic endocrine tumors (PET) can be difficult but is important because of differences in their clinical behavior. This study investigates the utility of immunohistochemistry (IHC) in this differential diagnosis using immunohistochemical stains that are available in most laboratories. IHC was performed on paraffin-embedded tissue in ACC (n = 6), MAEC (n = 2), and PET (n = 13), using synaptophysin (SYN), chromogranin (CHR), chymotrypsin (CHY), and alpha-1-antitrypsin (AAT). Electron microscopy (EM) was performed in all cases to confirm the diagnosis. Long-term follow-up and death of disease (DOD) was known in all patients. The ACCs stained as follows: CHY (4/6), AAT (3/6), SYN (4/6); CHR was negative in all cases. Both cases of MAEC stained with CHY, AAT, and SYN (2/2); CHR was negative. PET stained as follows: SYN (13/13), CHR (8/13), CHY (4/13), AAT (5/13). In the ACC/ MAEC group, six of eight patients were DOD at mean follow-up of 11 months. Among the PET, two of 16 patients were DOD at mean follow-up of 37 months. Considerable immunophenotypic overlap exists between ACC, MAEC, and PET. Consequently, one can neither confirm nor rule out a diagnosis of ACC or MAEC using generally available immunohistochemical stains alone. These findings support a role for EM in the evaluation of exocrine and endocrine pancreatic neoplasms.

Acinar-islet cell tumor of the pancreas: report of a malignant pancreatic composite tumor

An unusual case of malignant pancreatic composite tumor with both components of acinar cell tumor (ACT) and islet cell tumor (ICT) was investigated histologically, immunohistochemically, and ultrastructurally. The pancreatic tumor with central cyst formation was found on computerized tomographic examination of a 72-year-old man reporting appetite and weight loss. The ACT component was present in the original pancreatic region and the ICT region was adjacent to the ACT. ACT was immunohistochemically positive for pancreatic amylase, whereas ICT had argyrophil tumor cells immunohistochemically positive for chromogranin A. There were several tumor cell nests positive for both pancreatic amylase (acinar differentiation) and chromogranin A (islet differentiation). We speculated that ICT may have arisen from the de-differentiated tumor cells in the ACT after the occurrence of ACT.

Acinic cell carcinoma of the breast: an immunohistochemical and ultrastructural study

The clinicopathological features of six cases of breast carcinomas showing features of acinic cell differentiation, which are similar to those seen in homologous tumors of salivary glands, are presented. The patients, all women, were 35-80 years of age. One case recurred after 4 years, and in two cases axillary lymph node metastases were found at the time of surgery. Histologically the tumors showed a microglandular pattern merging with solid areas. Cytologically, immunohistochemically, and ultrastructurally the tumors were very similar to cases of acinic cell carcinoma of the parotid gland. The differential diagnostic criteria with microglandular adenosis and carcinomas showing granular cytoplasm are discussed. It seems that acinic cell carcinomas of the breast have to be added to the long list of tumors that affect the salivary glands and can also arise in the breast.

Unusual prostatic adenocarcinoma with endocrine basophilic FSH-immunoreactive cells

We report an unusual variant of prostatic adenocarcinoma with marked endocrine differentiation (mixed endocrine-exocrine adenocarcinoma). Endocrine cells accounted for 60% of the tumour cells, were positive with silver impregnation and for chromogranin A, synaptophysin, and neuron-specific enolase, and coexpressed the exocrine antigens prostatic acid phosphatase and prostatic-specific antigen. Most of the endocrine cells were basophilic with haematoxylin-eosin and proved immunoreactive for alpha subunit of human chorionic gonadotropin and follicle-stimulating hormone. The remaining endocrine cells were represented by eosinophilic cells positive for serotonin, and by calcitonin and serotonin-immunoreactive cells not identifiable in haematoxylin-eosin-stained sections. On ultrastructural analysis, two types of endocrine cells were identified. The most frequent cell type showed abundant cytoplasmic round, electron-dense neurosecretory granules, either small (212+/-44 nm) or large (471+/-114 nm), resembling those of gonadotropic pituitary cells. The second type of endocrine cells contained irregular electron-dense granules similar to those of serotonin-storing enterochromaffin cells.

Ultrastructural study of intranuclear inclusion bodies of pulmonary adenocarcinoma

Intranuclear inclusion bodies are sometimes observed in pulmonary adenocarcinoma by light microscopy. Electron microscopic characteristics of lung cancer cells with intranuclear inclusion bodies were studied. In addition, polymerase chain reaction (PCR) was performed using primers coding for human papillomavirus (HPV) types 16, 18, and 33. Eosinophilic intranuclear inclusion bodies were observed in 22 out of 285 cases by light microscopy. Immunohistochemically, cancer cell nuclei stained with PE-10. Three types of intranuclear inclusion bodies were classified electron microscopically. Type A showed aggregation of electron dense particles (30-40 nm) with an electron-dense core and was most frequently observed. Type B consisted of a mass of branching and whirling tubular structures. Type B intranuclear inclusions had a relationship with inner nuclear membrane. In type C, several spherical inclusions were observed in one nucleus. HPV DNA was detected using PCR and type-specific probes in a case with type A inclusion bodies. This study suggests that intranuclear inclusion bodies in pulmonary adenocarcinoma are formed by several different mechanisms.

[Pancreatoblastoma in adults]

Pancreatoblastoma is a rare pancreatic tumor, which usually occurs during childhood. We describe here the ninth adult case in a 21-year-old woman, who died 7 months after diagnosis despite complete surgical resection and adjuvant chemotherapy. Pancreatoblastoma in adults has a poor prognosis, at variance with what may be observed in childhood.

[Giant acinic cell parotid gland adenocarcinoma of the papillary- cystic type]

A case of a 38-year-old male having an acinic cell adenocarcinoma of the parotid gland is reported. The tumor measured 22 cm and histologically it was of the papillary-cystic type. The following features were of interest: 1) the tumor size surpassed the size of previous reported acinic cell adenocarcinomas by 9 cm; and 2) the rarity of its histological variety (cystic papillary) demanded immunohistochemical and electron microscopic studies to confirm the diagnosis.

Functioning pancreatic acinar cell carcinoma: immunohistochemical and ultrastructural analyses

Acinar cell carcinoma (ACC) of the pancreas is a rare malignancy accounting for < 1% of pancreatic neoplasms. We report the clinical and biological characteristics of this carcinoma from two cases that were of interest because of their similar presentation: extensive subcutaneous fat necroses from excessive lipase production by these tumors. Immunohistochemical and ultrastructural analyses of both tumors were consistent with an acinar cell line origin. Recognition of the association between subcutaneous panniculitis and pancreatic neoplasm may prevent long delays in the diagnosis and treatment of this malignancy.

Acinic cell-like carcinoma of the breast

A case of infiltrating carcinoma of the breast with features similar to those seen in acinic cell carcinoma of the parotid gland is described in a 42-year-old woman. The neoplastic cells were immunoreactive with anti-lysozyme- and anti-salivary-type amylase antisera and contained electron-dense cytoplasmic globules similar to those seen in acinic cell carcinoma of salivary glands. One lymph node out of 18 was found to contain a metastatic deposit. The patient is alive and well 1 year after mastectomy. This appears to be the first case of carcinoma with acinic cell-like features reported in the breast.

Helioid inclusions in dedifferentiated acinic cell carcinoma of the parotid gland

Helioid bodies are exceedingly rare, intranuclear, rounded inclusions with peripheral radiating filaments. These structures, which were formerly observed in only three cases of proliferative breast epithelial lesions, appeared in 0.5-1% of the neoplastic cells of a case of dedifferentiated acinic cell carcinoma of the parotid gland. Helioid bodies are related to rough endoplasmic reticulum cisternae, which suggests that they are the result of the condensation and partial crystallization of their contents when sequestrated into the nuclear compartment of the cell. The presence of helioid bodies may be related to secretory dysfunction of the tumor cells associated with the process of neoplastic dedifferentiation.

Fibrillary inclusions in neoplastic and fetal acinar cells of the pancreas

We report a case of pancreatic acinar cell carcinoma which contained a large number of pleomorphic inclusions with fibrillary internal structures and mature zymogen granules. To clarify the significance of fibrillary inclusions in the differentiation of acinar cells of the pancreas, we further investigated fetal pancreases (gestational weeks 16, 17, 19, 20 and 28). We found two types of inclusions: type A, corresponding to fibrillary inclusion of neoplastic acinar cells, was observed only in a 19-week fetus; type B showed a homogeneous density similar to that of zymogen granules. Type B was observed in all the fetuses after the 17th gestational week. Although the type A inclusion might be generated through a different mechanism than the type B inclusion, the appearance of a large number of fibrillary inclusions in neoplastic acinar cells may represent a transient form of zymogen granule.

Fine needle aspiration cytology of acinar cell carcinoma of the pancreas: a report of two cases

BACKGROUND

Fine needle aspiration in lieu of needle biopsy is widely used for the diagnosis of pancreatic neoplasms. The cytologic features of ductal carcinomas are well characterized, but the appearances of less common pancreatic neoplasms, such as acinar cell carcinoma (ACC), are not well described.

CASES

We present the cytologic, histologic, immunocytochemical and ultrastructural features of two cases of ACC. The tumors occurred in a 36-year-old woman and 43-year-old man. The aspirate from one case contained neoplastic cells with smooth-contoured nuclei containing one or two prominent nucleoli. The aspirated material from the second case was necrotic, with numerous neutrophils and scattered nests of tumor cells similar to those present in the first case. Histologically, both tumors manifested solid and acinar patterns, and each contained some cells with periodic acid-Schiff-positive granules that were resistant to diastase. The neoplasms were immunochemically positive for trypsin and negative for neuroendocrine markers. Ultrastructurally, the aspirate from one case demonstrated apical microvilli, zymogenlike granules and abundant rough endoplasmic reticulum.

CONCLUSION

Uncommon pancreatic neoplasms may be difficult to diagnose due to their cytologic and histologic subtleties. Supplemental studies including immunocytochemistry, cytochemistry and electron microscopy are important in facilitating their identification.

Filamentous inclusions in nonneoplastic and neoplastic pancreas: an ultrastructural and immunogold labeling study

Filamentous inclusions (FI) are unusual, irregularly shaped cytoplasmic inclusions, which are mostly found in acinar cell carcinomas of the pancreas and are consequently thought to be an abnormal zymogen granule type. This study describes identical inclusions in acinar, centroacinar, and small duct epithelial cells from nonneoplastic pancreas, as well as those found in tumor cells from a mixed acinar-endocrine pancreatic carcinoma. An ultrastructural and immunogold labeling demonstration indicates that these inclusions are aggregates of intermediate filaments immunoreacting with the anti-cytokeratin AE1/AE3 mixture and with V9 clone anti-vimentin monoclonal antibodies. Their pleomorphic appearance, variable immunoreactivity, and frequent association with lipid droplets and secondary lysosomes, mostly of the angulate type, led to the hypothesis that the FI undergo a degenerative remodeling pathway similar to that proposed for hepatic Mallory bodies. A survey of the literature on FI and human tumors suggests that they are a variably expressed ultrastructural feature of tumor cells originating from exocrine cell-containing tissues, namely the pancreas and gastrointestinal tract.

Unusual intracytoplasmic inclusions in metastatic carcinoma. Discussion of their possible significance

Unusual filamentous inclusion bodies in the cytoplasm of metastatic tumor cells are described. Their presence (intermingled with zymogen granules) seems rather restricted to cells of primary or metastatic acinar cell carcinoma of the pancreas, acinic carcinoma of salivary gland (parotid gland) and Paneth cells (neoplastic or in zinc deficiency state). For the time being, the real nature of these inclusions (deranged zymogen granules?) is unclear. This case also emphasizes the value of electron microscopy in solving the problem of the occult primary tumor and avoiding the misdiagnosis of an endocrine tumor (e.g. islet cell tumor or carcinoid), or a duct cell tumor with eosinophilic granular cytoplasm or in recognizing the foci of acinar cells in a mixed variant of carcinoma of the pancreas.

Acinar cell carcinoma of the pancreas. Report of three cases

Pancreatic acinar cell carcinoma is a rare neoplasm (comprising about 1% of pancreatic tumours). We studied three cases (61-year-old female; 42-year-old male; 57-year-old male), whose survival after diagnosis ranged from 1 year 2 months to 6 years 8 months. There were widespread metastases in each case. The tumours had acinar, trabecular and solid growth patterns. By immunohistochemistry, pancreatic acinar cell markers including carboxyl ester lipase, pancreatic secretory trypsin inhibitor and pancreatic phospholipase A2 (group I PLA2) gave a strong positive reaction in all three cases. By electron microscopy, zymogen granules were seen in the cytoplasm of the tumour cells. Immunostaining for prostate-specific antigen was positive in all three cases. Above-normal concentrations of pancreatic PLA2 were measured in the serum of one patient and the values decreased during chemotherapy concomitantly with the reduction in the size of the tumour mass. In conclusion, immunohistochemical demonstration of the secretory products of acinar cells including the new marker pancreatic PLA2 is useful in the differential diagnosis of pancreatic acinar cell carcinoma. Determination of the concentration of pancreatic group I PLA2 in serum may be helpful in the evaluation of therapy.

Mixed acinar-endocrine carcinomas of the pancreas

Acinar cell carcinoma is a rare pancreatic neoplasm that may contain scattered endocrine cells in as many as 40% of cases. In addition, unusual tumors exist in which the acinar and endocrine components each constitute a significant proportion (> 25%) of the neoplasm; we propose to designate them as "mixed acinar-endocrine carcinomas." In a study of five such cases, we found one case with segregated areas of acinar and endocrine cells that were identifiable in routinely stained sections and four cases with morphologically uniform cell populations where the divergent differentiation was only detected immunohistochemically. The tumors occurred in adults (age range, 48-81; mean, 68); there were two men and three women. None of the patients presented with symptoms related to either enzyme or hormone liberation. Histologically, the tumors were very cellular; various combinations of solid, trabecular, acinar, and glandular growth patterns were noted. The cells contained d-PAS-positive granules and showed immunohistochemical positivity for pancreatic enzymes (trypsin, chymotrypsin, and lipase) and endocrine markers (chromogranin and synaptophysin); specific endocrine hormones were found in two cases. Double immunohistochemical staining for acinar and endocrine markers showed that most cells expressed only one line of differentiation. Ultrastructural study of two cases showed two populations of granules. Two of the patients died of their tumors (mean survival, 10.5 months), one with widespread metastases. Two patients were alive with disease at 12 months after diagnosis, and one patient was lost to follow-up after 3 months. This rare type of pancreatic neoplasm provides further evidence of the close histogenetic relationship between the exocrine and endocrine components of this organ.

Needle aspiration cytology of acinar-cell carcinoma of the pancreas: report of a case with diagnostic pitfalls and unusual ultrastructural findings

A case of histologically and ultrastructurally confirmed acinar-cell carcinoma of the pancreas examined by needle aspiration cytology is reported. The aspirate showed isolated and loosely clustered cells with variable granular cytoplasm, and central or eccentrically located oval hyperchromatic nuclei displaying prominent nucleoli, suggesting a pancreatic neuroendocrine tumor. Numerous intracytoplasmic zymogen granules and several microtubules within cisternae of rough endoplasmic reticulum (MCRER) were found by electron microscopic study of metastatic tumor tissue. Cytodiagnostic pitfalls of this rare pancreatic cancer are discussed as well as the diagnostic value of MCRERs.

Intermediate filaments in rat pancreatic acinar tumors, human ductal carcinomas, and other gastrointestinal malignancies

BACKGROUND/AIMS

Keratin is a member of the intermediate filament family in epithelial cells. Two-dimensional gel electrophoresis of different epithelial cells has shown 20 different keratin polypeptides. Therefore, mapping of the keratin polypeptides can be used to define a specific tissue.

METHODS

Cytokeratin expression was investigated by using monoclonal antibodies in human surgical specimens and autopsy material of pancreatic, gastric, liver, and colon carcinomas and cholangiocarcinomas, and their metastasis to lymph nodes and liver was examined. In addition, rat acinar cell carcinomas were used to compare cytokeratin expression in ductal vs. acinar cell pancreatic carcinomas.

RESULTS

Human pancreatic ductal carcinomas expressed keratins 7, 8, 18, and 19, whereas the majority of rat acinar carcinomas did not express keratins typical for ducts in rat pancreas. The keratin patterns of gastric and colon carcinomas were identical with keratins 8, 18, and 19. In contrast, hepatocellular carcinomas expressed the same keratin pattern as pancreatic acinar carcinomas with keratins 8 and 18, whereas cholangiocarcinomas expressed keratin 7, 8, 18, and 19, similar to pancreatic ductal carcinomas. Metastasis of pancreatic ductal and colon carcinomas retained their keratin patterns.

CONCLUSIONS

Keratin polypeptide typing of unknown malignant cells can be a useful tool for cell identification.

Ultrastructure of normal and neoplastic exocrine pancreas in the mummichog, Fundulus heteroclitus

The ultrastructure of exocrine pancreatic neoplasms occurring in the mummichog, Fundulus heteroclitus, from a creosote-contaminated site in the Elizabeth River, Virginia, is described and related to nonneoplastic exocrine pancreas. Normal mummichog pancreas was an anastomosing tubular gland, with parenchymal cells organized as branched, anastomosing tubules around a central ductular system. The pancreatic ductular system consisted sequentially of terminal canalicular lumens lined by acinar cells, pancreatic preductules formed by an acinar and a centroductular cell, pancreatic ductules lined by 2 centroductular cells, and pancreatic ducts lined by cuboidal or columnar epithelial cells resting on a basal lamina and stromal sheath. Acinar cell adenomas retained the normal tubular organization and relationship between acinar and centroductular cells. Tumor cells exhibited nuclear pleomorphism but contained a full complement of normal zymogen granules and rough endoplasmic reticulum (RER). Some adenomas exhibited necrosis and cellular degeneration. Acinar cell carcinomas ranged from well to poorly differentiated. They exhibited loss of cell polarity, moderate to severe nuclear pleomorphism, extensive variation in size, shape, and number of zymogen granules, variability in RER content, and cellular degeneration. Acinar cell neoplasms in the mummichog were similar to those induced chemically in other fishes and certain mammals, suggesting that this fish population has been exposed to potent chemical carcinogens and that the species may be an effective indicator of polluted estuarine environments.

Filamentous inclusions in acinar cell carcinoma of the pancreas

Acinar cell carcinoma of the pancreas exhibits a spectrum of histologic appearances. Some tumors can be readily identified by light microscopy, but others resemble endocrine/neuroendocrine neoplasms. Ultrastructurally, though large zymogen granules of acinar cells are usually distinctive, the zymogen granules of neoplastic acinar cells are sometimes abnormally small, overlapping in size with the granules of endocrine/neuroendocrine neoplasms. Six cases of acinar cell carcinoma, two with a typical histologic appearance and four that resembled endocrine/neuroendocrine tumors, were studied ultrastructurally. In addition to zymogen granules and abundant rough endoplasmic reticulum, all cases of acinar cell carcinoma exhibited pleomorphic, membrane bound inclusions that contained filaments. Similar inclusions were not identified in islet cell or carcinoid tumors, and several findings indicate that the inclusions represent deranged zymogen granules. In the ultrastructural study of a pancreatic neoplasm with granules, these inclusions may provide a clue for the diagnosis of acinar cell carcinoma.

Acinar cell carcinoma of the pancreas. A histologic, immunocytochemical and ultrastructural study

A rare case of acinar cell carcinoma of the pancreas is presented. Because of its unusual solid growth pattern, correct diagnosis required electron microscopic analysis and the demonstration of intracellular amylase by immunohistochemical stains. The presence of pleomorphic electron-dense cytoplasmic granules containing fibrillary internal structures is confirmed in this ultrastructural study. The differential diagnosis of acinar cell carcinoma from other neoplasms involving the pancreas, including neuroendocrine tumours, poorly-differentiated adenocarcinomas and neoplasms of putative acinar cell derivation, is discussed.

Immunopathology of phenotypic change on human parotid gland adenocarcinoma

Immunopathological analysis was made of phenotypic change in a recurrent parotid gland adenocarcinoma occurring in a patient with a long clinical course of 30 years or more. At the first and second operations, in 1959 and 1978, the resected parotid gland tumors were diagnosed histopathologically as acinic cell carcinoma. However, 11 years after the second operation, in 1989, the resected recurrent tumor showed a microscopically phenotypic change towards adenocarcinoma with typical tubular arrangement. At the last operation in 1991, histopathological examination of the tumor revealed adenocarcinoma with diffuse oncocytic change in association with cervical lymph node metastasis. These findings suggest that phenotypic change may occur in vivo among human neoplasms during a long period, which may be related to the cytodifferentiation in the salivary gland tumor.