Polymorphisms in the 3'-untranslated region of the CDH1 gene are a risk factor for primary gastric diffuse large B-cell lymphoma.

BACKGROUND: Primary gastric B-cell lymphomas arise from mucosa-associated lymphatic tissue (MALT) in patients with chronic Helicobacter pylori infection. We investigated whether germline variants in the CDH1 gene, coding for E-cadherin, genetically predispose patients to primary gastric B-cell lymphoma. DESIGN AND METHODS: Single marker analyses of the CDH1 gene were conducted in patients with primary gastric B-cell lymphoma (n=144), in patients with primary gastric high-grade lymphoma (n=61), and in healthy blood donors (n=361). Twelve single nucleotide polymorphisms were genotyped by TaqMan(®) technology. Allelic imbalance was tested by pyrosequencing and clone direct sequencing of heterozygote genomic and cDNA. Mutation detection was conducted around the poly-A signal of the CDH1 3'-untranslated region. The influence of the 3'-untranslated region on protein translation was determined by a luciferase reporter assay. RESULTS: Single marker analyses identified two single nucleotide polymorphisms in strong linkage disequilibrium located in the CDH1 3'-untranslated region. One of them was significantly associated with primary gastric diffuse large B-cell lymphomas after correction for multiple testing and this association was confirmed in an independent sample set. Patients homozygous for the rare T allele (rs1801026) had a 4.9-fold increased risk (95% CI: 1.5-15.9) of developing primary gastric diffuse large B-cell lymphoma. Allelic imbalance and reporter gene assays indicated a putative influence on mRNA stability and/or translational efficacy. CONCLUSIONS: We identified variants in CDH1 as the first potential genetic risk factors for the development of primary gastric diffuse large B-cell lymphomas. One of the potentially causative variants affects allelic CDH1 expression. These findings support the hypothesis that besides somatic alterations of B-cells, germline variants in the CDH1 gene contribute to a predisposition to the development of primary gastric diffuse large B-cell lymphomas.

Pancreatic intraductal papillary-mucinous neoplasms: a new and evolving entity.

For a long time, intraductal tumors of the pancreas were neglected because they were misdiagnosed as mucinous cystadenocarcinoma, ordinary ductal adenocarcinoma, or chronic pancreatitis. Only in recent years have they been recognized as clinical and pathological entities. Most common are the intraductal papillary-mucinous neoplasms. Although they show an adenoma-carcinoma sequence, they have proved to have a more favorable prognosis than ductal adenocarcinoma, when resected in a preinvasive state. Recently, it has become clear that they constitute a heterogeneous group with at least four subtypes. Their stratification reveals that the various intraductal papillary-mucinous neoplasm subtypes have different biological properties with different prognostic implications.

Poorly differentiated endocrine carcinoma and intraductal papillary-mucinous neoplasm of the pancreas: Description of an unusual case.

Neuroendocrine tumors and intraductal papillary-mucinous neoplasms constitute histologically distinctive but relatively rare entities among pancreatic tumors. Collision of these tumors is extremely rare and causes several diagnostic problems regarding the histopathologic differential diagnosis of other pancreatic epithelial tumors. The question of whether the neoplastic populations originate from common progenitor cell or whether they represent only a fortuitous association has not been sufficiently explained. Here, we describe a new case of poorly differentiated endocrine carcinoma combined with an intraductal papillary-mucinous neoplasm. To disclose the relationship between the two histologic components, neuroendocrine differentiation was studied by confocal laser scanning microscopy using double immunofluorescence labeling with chromogranin-A and CD57 antibodies. Our results revealed a co-localization of both antigens in neuroendocrine cells of the intraductal papillary-mucinous neoplasm. The finding has previously been described in non-neoplastic neuroendocrine cells. Cells forming poorly differentiated endocrine carcinoma showed a wide heterogeneity in immunoreactions. Our results do not indicate a potential histogenetic similarity between these two neoplasms, which are dissimilar histologically, and underline the previous thesis that cells in intraductal papillary-mucinous neoplasm revealing neuroendocrine differentiation represent only a non-neoplastic cell admixture.

Man as living bioreactor: fate of an exogenously prepared customized tissue-engineered mandible.

In 2004, we reported a novel method of repairing a human mandible by in vivo tissue engineering. The patient served as his own bioreactor as the exogenously prepared customized mandible replacement was grown inside his latissimus dorsi muscle prior to transplantation to repair the existing defect. Our technique was developed through extensive experience with an animal model. We describe our and the patient's experiences with this procedure. We give details to the benefits and limitations of this technique as it stands and outline issues that should be addressed in future human clinical trials.

Pancreatic solid and cystic hamartoma in adults: characterization of a new tumorous lesion.

Nonneoplastic tumor-like lesions ("pseudotumors") of the pancreas include cystic and noncystic varieties. We report on a solid and cystic tumor-like lesion of the pancreas that occurred in 2 adult patients. The lesions, located in the head and neck of the gland, respectively, were well demarcated and composed of cystic ductal structures embedded in focally inflamed stromal tissue. In addition, one of the lesions showed irregularly arranged but well-differentiated acini and small intralobular and interlobular ducts embedded in hypocellular, fibrotic tissue. Discrete islets were lacking, but immunohistochemical staining for chromogranin A revealed individual scattered endocrine cells evenly distributed between acinar and ductal cells. The surrounding pancreatic parenchyma did not show significant chronic pancreatitis. After tumor removal, the follow-up of the patients was uneventful. Because of the irregular arrangement of otherwise mature tissue components of the pancreas, the lesions were considered solid and cystic hamartomas. Their pathogenesis is so far unknown.

Serous cystic neoplasms of the pancreas: an immunohistochemical analysis revealing alpha-inhibin, neuron-specific enolase, and MUC6 as new markers.

Serous cystic neoplasms (SCNs) of the pancreas include serous microcystic adenoma (SMA), serous oligocystic ill-demarcated adenoma (SOIA), solid serous adenoma (SSA), von Hippel-Lindau-associated cystic neoplasm (VHL-CN), and serous cystadenocarcinoma (SCC). These neoplasms are histologically similar but differ in their localization, gross appearance, gender distribution, and biology. A centroacinar origin is assumed but has not been proven. To clarify whether the various subtypes of SCN may be distinguished from each other by marker profiles that might also provide evidence of their origin, the immunoprofiles of 38 SCNs (21 SMAs, 13 SOIAs, 2 VHL-CNs, 1 SSA, and 1 SCC) were defined by applying antibodies against cytoskeletal, neuroendocrine, hormone receptor, and mucin markers. In addition, we examined the expression of calretinin and alpha-inhibin. The various types of SCN showed a very similar immunoprofile, characterized by positivity for cytokeratins and neuron-specific enolase and negativity for vimentin and synaptophysin. Further markers that were commonly expressed in SCNs were alpha-inhibin (SMAs: 76%, SOIAs: 92%, VHL-CNs: 100%), MUC6 (SMAs: 60%, SOIAs: 85%, VHL-CNs: 100%), and MUC1 (SMAs: 24%, SOIAs: 38%, VHL-CNs: 50%). Western blot analysis in one SMA revealed a distinct band that stained with neuron-specific enolase antiserum. Alpha-inhibin was only expressed in 4 of 11 acinar cell carcinomas and not in five ductal adenocarcinomas, five neuroendocrine tumors, one mixed ductal-endocrine carcinoma, and one acinar cell cystadenoma of the pancreas. These results suggest that, despite their biologic differences, the various types of SCNs are composed of the same (or a very similar) cell type and may therefore have a common direction of differentiation. This notion is further supported by the finding that neuron-specific enolase, alpha-inhibin, and MUC6, which may be regarded as new markers for this pancreatic tumor type, were also expressed in most SCNs. Because a number of SCNs share MUC1 and MUC6 expression with the pancreatic centroacinar cells, the possibility of a histogenetic relationship has to be considered.

Acinar cell cystadenoma of the pancreas: a new entity?

This report describes a newly observed cystic lesion of the pancreas showing acinar cell differentiation. The patients affected by this lesion included seven women and three men (age range 16-66 years). In six patients, all of whom were female and all but one of whom suffered from abdominal pain, the cystic lesions (diameters, 4-15 cm) were detected by imaging techniques and subsequently removed. In four patients the cystic lesions were incidental findings. Eight lesions occurred as unifocal, unilocular or multilocular cysts in the head (n = 6) or tail (n = 2) of the pancreas. One lesion was bifocal (head and tail) and another involved the entire pancreas. The cysts were only rarely connected with the pancreatic duct system, but with acinar structures. Their lining cells expressed pancreatic enzymes and lacked any cellular atypia or proliferative activity (Ki67 index <1%). For a follow-up period of 6-84 months all patients remained alive and well. Although a nonneoplastic nature cannot be fully excluded, we propose that this lesion, composed of well-differentiated acinar cells, may represent the benign counterpart of the well-recognized acinar cystadenocarcinoma. We therefore suggest the term acinar cell cystadenoma.

Mixed acinar-endocrine carcinoma of the pancreas. A clinicopathological study and comparison with acinar-cell carcinoma.

We compared the clinicopathological features of acinar-cell carcinomas (ACCs) with those of mixed acinar-endocrine carcinomas (MAECs). Specimens from 37 patients with ACC and 6 patients with MAEC were examined histologically and immunohistochemically. The mean age of ACC and MAEC patients was similar (61.3 years versus 58.4 years), but the sex ratio differed (ACC, 29 males and 8 females; MAEC, 2 males and 4 females). The size of the tumor was large in both cases (ACC, 13.8 cm in diameter; MAEC, 8.2 cm). Immunohistochemically, more than half of the tumor cells in all tumors, whether ACC or MAEC, stained for trypsin. In 20 of the 37 ACCs (54%), scattered endocrine cells (SECs) were found, which stained positively for synaptophysin (SYN) and/or chromogranin A (CGA). Interestingly, there was also a difference in the sex ratio between ACC patients without SECs (16 males and 1 female) and ACC patients with SECs (13 males and 7 females). In MAECs, the cells staining for SYN were more common than those staining for CGA and made up more than one-third of the neoplastic-cell population. In all but one case (in which the endocrine component was arranged in islet-like cell clusters), the endocrine cells were intimately mixed with trypsin-positive tumor cells. The endocrine cells only rarely expressed one of the known pancreatic or gastrointestinal hormones. Both ACCs and MAECs had a high proliferation rate and lacked p53 overexpression or progesterone and estrogen receptors. This study revealed that ACCS and MAECs share most clinicopathological features and, therefore, may form a single tumor entity, though they differ in the number of endocrine cells. The frequent identification of endocrine cells in these tumors suggests the existence of a pluripotent cell of origin that is capable of differentiating into acinar and endocrine cells.

Solid pseudopapillary neoplasms of the pancreas show an interruption of the Wnt-signaling pathway and express gene products of 11q.

Solid pseudopapillary neoplasms of the pancreas almost consistently show a beta-catenin mutation activating the Wnt-signaling pathway, resulting in overexpression of cyclin D1, but not in overt malignancy of this tumor. Besides cyclin D1, a set of markers (ie FLI-1, CD56 and progesterone receptor), whose genes map to chromosome 11q, are frequently expressed in solid pseudopapillary neoplasms. Chromosome 11q is a region that is also often affected in pancreatic neuroendocrine tumors. This immunohistochemical study was undertaken to gain insights into the downstream regulation of the Wnt-signaling pathway and the significance of overexpressed gene products belonging to chromosome 11q for the tumorigenesis in solid pseudopapillary neoplasms. Fourteen solid pseudopapillary neoplasms were analyzed for the expression of cyclin-dependent kinase inhibitors p21, p27, p16 and hyperphosphorylated retinoblastoma (pRb) proteins. In an extended series of 93 solid pseudopapillary neoplasms, beta-catenin, cyclin D1, FLI-1 and CD56 expression was examined and compared with that in 22 pancreatic neuroendocrine tumors. Solid pseudopapillary neoplasms (98%) showed aberrant expression of beta-catenin with a concomitant cyclin D1 expression in 69% of the cases, but no expression of pRb (0%) was found. p27 and p21 were expressed in 100% (14/14) and 86% (12/14) of the cases, but only 2/14 (14%) were positive for p16. FLI-1 was expressed in 63% of solid pseudopapillary neoplasms, but only in 1/22 pancreatic neuroendocrine tumors (5%), cyclin D1 expression was present in 14% of the latter. We conclude that in solid pseudopapillary neoplasms the activated Wnt-signaling pathway is disrupted, and that p21 and p27 are contributing to this fact by blocking of the hyperphosphorylation of the Rb protein, thus causing the very low proliferation rate characterizing the solid pseudopapillary neoplasms. The accumulation of high expression of proteins whose genes are located on chromosome 11q is characteristic of solid pseudopapillary neoplasms, but not of pancreatic neuroendocrine tumors.

Solid pseudopapillary neoplasms of the pancreas are associated with FLI-1 expression, but not with EWS/FLI-1 translocation.

Solid pseudopapillary neoplasms of the pancreas are rare pancreatic tumors with mostly benign behavior, affecting almost exclusively women. Their histogenetic origin is still unsolved, but a recently reported EWS/FLI-1 translocation t(11;22)(q24;q21) and the consistent expression of CD56 and the progesterone receptor, both genes located on the long arm of chromosome 11, point to chromosome 11q as a potential locus of gene aberration in solid pseudopapillary neoplasms. To further elucidate this issue, we studied 30 cases of solid pseudopapillary neoplasms by comparative genomic hybridization (CGH), fluorescent in situ hybridization (FISH) and immunohistochemistry. Immunohistochemically, 38% showed nuclear expression of FLI-1 and all cases revealed positivity for CD56 and the progesterone receptor, whereas no solid pseudopapillary neoplasm expressed CD34. No translocation of the EWS gene was found by FISH and no gross chromosomal gain or loss was detected by CGH. It is concluded that FLI-1 expression in solid pseudopapillary neoplasms is not associated with an EWS/FLI-1 translocation. In addition, there are no chromosomal gains or losses, especially on chromosome 11, where the FLI-1 gene is located adjacent to the gene for CD56 (NCAM). These data add another feature to the complex phenotypic appearance of solid pseudopapillary neoplasms.

Pancreatic ductal adenocarcinomas with cystic features: neither rare nor uniform.

Cystic tumors of the pancreas are uncommon but important because of their diverse pathology and biology. Their wide spectrum also includes cystic variants of otherwise solid tumors, such as cystic endocrine tumors, cystic acinar cell carcinomas and ductal adenocarcinomas with cystic changes. In this study, we screened pancreatic ductal adenocarcinomas and their variants for macrocystic changes and determined the nature of the cysts (neoplastic vs non-neoplastic). Of 483 tumors 38 (8%) had cystic features. The largest group consisted of 24 pancreatic ductal adenocarcinomas showing a large-gland pattern with small cysts whose diameter varied between 0.5 and 1.8 cm. The epithelial lining of these cysts was generally positive for CEA (83%) and/or MUC1 (71%) and MUC5AC (74%). p53 was positive in 57% of the cases. The second group of cystic tumors (8/483) showed degenerative cystic cavities with diameters ranging between 1 and 6 cm. This group consisted of poorly differentiated pancreatic ductal adenocarcinomas, undifferentiated carcinomas with or without osteoclast-like giant cells and one adenosquamous carcinoma. In the third group of cystic tumors there were four pancreatic ductal adenocarcinomas containing tumor-related retention cysts. Their epithelial cells were positive for MUC5AC, but negative for CEA, MUC1 and p53. The fourth group consisted of two pancreatic ductal adenocarcinomas showing closely attached pseudocysts caused by tumor-associated pancreatitis. The results indicate that a considerable number of pancreatic ductal adenocarcinomas and their variants display cystic features and must therefore be considered in the differential diagnosis of cystic neoplasms of the pancreas. Moreover, not all of the cystic structures we observed were neoplastic in nature. They may also represent non-neoplastic changes, such as retention cysts and inflammatory pseudocysts.

Life-threatening chronic enteritis due to colonization of the small bowel with Stenotrophomonas maltophilia.

Chronic diarrheal illness and malabsorption are challenging diagnostic and clinical problems. The identification of the causative pathogens that are involved in gastrointestinal infections is often difficult. It took 85 years after the first description of a case of intestinal lipodystrophy by Georg Whipple in 1907 until the causative bacterium was characterized by using molecular genetics techniques. We here report the complicated clinical course of a young patient with chronic diarrhea accompanied by severe, life-threatening malabsorption with extensive weight loss. Histology and glucose hydrogen breath test were suggestive of a bacterial overgrowth syndrome in the small bowel, but standard culture-based techniques and serology failed to identify the causative bacteria. Thus, bacterial ribosomal DNA (16S ribosomal DNA) was extracted from duodenal biopsy samples and analyzed by community fingerprinting and species-specific polymerase chain reaction. Stenotrophomonas maltophilia was identified as the cause of chronic infectious enteritis. Only specific long-term antibiotic treatment with co-trimoxazole had a durable clinical effect and led to normalization of 16S ribosomal DNA profiles. This case shows the role of rare and uncommon bacteria in refractory and chronic human gastrointestinal infections. Genomic techniques, including 16S-based single-strand conformation polymorphism analysis, will play an increasing role in the diagnosis of chronic infections with facultatively pathogenic bacteria or in the clinical analysis of complex bacterial communities such as the intestinal bacterial microflora. Future enhancements in detection techniques will show that chronic bacterial infections are more frequent as a cause of gastrointestinal malfunction than commonly thought.

Mucinous nonneoplastic cyst of the pancreas: a novel nonneoplastic cystic change?

Cystic lesions and neoplasms of the pancreas are uncommon, but they are of special interest because they can usually be cured by resection. During the last decade, the spectrum of these tumors has increased considerably. We present a series of five cystic lesions of the pancreas that differ from all categories described so far. The patients affected by these tumors were three men and two women (mean age, 57 y). Four lesions were unifocal and involved the head of the pancreas; one was multifocal and involved the pancreatic head and tail. Grossly, these tumors presented as unilocular or multilocular thin-walled cysts that contained turbid fluid, or, in two cases, blood, and lacked any communication with the duct system. Microscopically, the cysts were lined by cuboidal to columnar mucin-producing cells, supported by a small band of dense fibrous stroma. Immunocytochemically, the epithelial cells were positive for cytokeratins 7, 8, 18, 19, and 20 (except one), and Ca 19-9 but were negative for trypsin, CEA, synaptophysin, chromogranin A, calretinin, and alpha-inhibin. In four of the five lesions, the epithelial cells expressed MUC5AC, and in one of the five, MUC1. MUC2 and MUC6 were not expressed in any of the lesions. The stromal cells lacked the nuclear progesterone positivity that is typical of mucinous cystic neoplasms. During a mean follow-up period of 2 years, there were no recurrences or cases of malignant transformation after resection. The results suggest that these cystic lesions are distinct from mucinous cystic neoplasms, the most important entity in the differential diagnosis. Because they may represent a nonneoplastic cystic change of the pancreas, we propose the descriptive term mucinous nonneoplastic cyst for these tumors of unknown pathogenesis.