Sporadic fundic gland polyps: common gastric polyps arising through activating mutations in the beta-catenin gene

Fundic gland polyps (FGPs) are the most common gastric polyps. FGPs traditionally have been regarded as nondysplastic hamartomatous or hyperplastic lesions, but their pathogenesis remains unclear. We have recently shown that somatic adenomatous polyposis coli (APC) gene alterations are frequently present in FGPs associated with familial adenomatous polyposis (FAP), raising the possibility that mutations of the beta-catenin gene affecting the APC/beta-catenin pathway might be involved in the pathogenesis of sporadic FGPs. We analyzed somatic beta-catenin gene mutations in 57 sporadic FGPs from 40 patients without FAP and in 19 FGPs from 13 FAP patients. Direct DNA sequencing of exon 3 encompassing the glycogen synthase kinase-3beta phosphorylation region for beta-catenin was used with confirmation by HIN:fI restriction endonuclease digestion. The foveolar epithelium and dilated fundic glands of the polyps were separately microdissected and analyzed in 22 of 57 sporadic FGPs. Activating beta-catenin gene mutations were present in 91% (52 of 57) of sporadic FGPs. Both the foveolar epithelium and the dilated fundic gland epithelium comprising the polyps were shown to have the same somatic beta-catenin mutation in 21 of 22 (95%) sporadic FGPs. In contrast, beta-catenin gene mutations were not present in any of the 19 FAP-associated FGPs (P: < 0.000001). The high frequency of beta-catenin mutations in sporadic FGPs indicates that these lesions arise through activating mutations of the beta-catenin gene. Beta-catenin mutations in gastrointestinal tract polyps have previously only been demonstrated in a subset of adenomatous (dysplastic) or neoplastic polyps. Sporadic FGPs are therefore the only lesions of the gastrointestinal tract to demonstrate beta-catenin mutations while lacking dysplastic morphology.

Hyperplastic polyps of the colorectum-innocent or guilty?

Hyperplastic polyps have traditionally been regarded as nonneoplastic polyps lacking malignant potential. The demonstration of genetic alterations within these lesions indicates an underlying neoplastic cause. There is evidence that hyperplastic polyps are heterogeneous. Most are innocuous, but subsets may have malignant potential. Risk factors for neoplastic progression include multiple, large, and proximally located polyps. Aberrant methylation resulting in the silencing of cancer genes may be an important underlying mechanism, particularly in pathways progressing to tumors with DNA microsatellite instability. Lesions intermediate between hyperplastic polyp and cancer include admixed polyps and serrated adenomas. Currently, pathologists have different thresholds for diagnosing serrated adenomas, including the distinction from large hyperplastic polyps. Reasons for over looking this pathway in the past may include rapid tumor progression and the fact that proximally located hyperplastic polyps may be flat and not especially numerous. Management of the serrated pathway of colorectal neoplasia may require novel approaches to screening, early detection, and prevention.

Hyperplastic polyposis: association with colorectal cancer

Hyperplastic polyposis is a loosely defined syndrome initially thought not to confer a clinically important predisposition to colorectal cancer. The aim of the current study was to examine the clinical, histologic, and molecular features of a prospective series of cases meeting a strict definition of the condition. Twelve patients were identified, seven of whom had developed colorectal cancer. Most polyps were hyperplastic, but 11 patients also had polyps containing dysplasia as either serrated adenomas. mixed polyps, or traditional adenomas. The mean percentage of dysplastic polyps in patients with cancer was 35%, and in patients without cancer, 11% (p < 0.05). Microsatellite instability (MSI) was present in 3 of 47 hyperplastic polyps and two of eight serrated adenomas. Kras was mutated in 8 of 47 hyperplastic polyps and two of eight serrated adenomas. No polyps showed loss of heterozygosity of chromosomes 5q, 1p, or 18q. Two of seven cancers showed a high level of MSI. It is concluded that hyperplastic polyposis is associated with a high risk of colorectal cancer. Hyperplastic polyps are the dominant type of polyp, but most cases have some dysplastic epithelium. A higher proportion of dysplastic polyps is associated with increased cancer risk. Clonal genetic changes are observed in some hyperplastic polyps and serrated adenomas.

p53, but not c-Ki-ras, mutation and down-regulation of p21WAF1/CIP1 and cyclin D1 are associated with malignant transformation in gastric hyperplastic polyps

To investigate tumorigenesis in the gastric hyperplastic polyp (HP), we evaluated 19 HPs with and 50 HPs without dysplasia (including carcinoma in situ), as compared with normal mucosa and fundic gland polyps. Helicobacter pylori density was highest in HPs without dysplasia. Apoptotic activity and Ki-67 and p53 expression also were higher in dysplasia in HPs than in normal mucosa, fundic gland polyps, or HPs themselves. The p21WAF1/CIP1 and cyclin D1 levels, in contrast, were highest in HPs. In HPs without dysplasia, size was correlated positively with the degree of stromal inflammation and with p53 and cyclin D1 expression. p53 and c-Ki-ras mutations were detected in 41% (8/19) and 5% (1/19) of dysplasia (including carcinoma in situ) in HPs. Our results demonstrate that the HP enlarges with enhanced cell turnover and overexpression of p53, p21WAF1/CIP1, and cyclin D1, associated with H pylori-related inflammation, and that p53 but not c-Ki-ras mutations may have an important role in dysplastic change in HPs.

Fundic gland polyps in familial adenomatous polyposis: neoplasms with frequent somatic adenomatous polyposis coli gene alterations

Fundic gland polyps (FGPs) are the most common gastric polyps in patients with familial adenomatous polyposis (FAP). FGPs have traditionally been regarded as nonneoplastic, possibly hamartomatous lesions, but the pathogenesis of FGPs in both FAP and sporadic patients remains unclear. FGPs in FAP can show foveolar dysplasia, and rarely invasive gastric adenocarcinoma has been reported in patients with FAP and fundic gland polyposis. Using direct gene sequencing and allelic loss assays at 5q, we analyzed somatic adenomatous polyposis coli (APC) gene alterations in 41 FAP-associated FGPs (20 with foveolar dysplasia, six indefinite for dysplasia, and 15 nondysplastic) and 13 sporadic FGPs. The foveolar epithelium and dilated fundic glands of the polyps were separately microdissected and analyzed in 25 of 41 FAP-associated FGPs and 13 of 13 sporadic FGPs. Somatic APC gene alterations were identified frequently (21 of 41 cases, 51%) in FAP-associated FGPs. Both the foveolar epithelium and the dilated fundic gland epithelium comprising the FGPs were shown to carry the same somatic APC gene alteration in 24 (96%) of 25 cases. Furthermore, there was no difference in the frequency of somatic APC gene alterations between FGPs with foveolar dysplasia (10 of 20, 50%), indefinite for dysplasia (four of six, 67%), and nondysplastic (seven of 15, 47%) in FAP patients (P: = 0.697). In contrast, FGPs from non-FAP patients showed infrequent (one of 13, 8%) APC gene alterations (P: = 0.008). These results show that FGPs in FAP patients are pathogenetically distinct from sporadic FGPs. Somatic, second-hit APC gene alterations, which precede morphological dysplasia in many FAP-associated FGPs, indicate that FGPs arising in the setting of FAP are neoplastic lesions.

Identification of the origin of a vesical mass occurring after cadaveric renal transplantation using short tandem repeat markers

We report a case of polypoid cystitis in a 54-year-old female occurring 4 years after cadaveric kidney transplantation. Endoscopic exploration revealed a polypoid tumor near the stoma opened for the transplanted ureter. The diagnosis of polypoid cystitis was confirmed histopathologically. Genotyping of cells from the tumor with polymorphic short tandem repeat (STR) and amelogenin loci revealed that the tumor contained alleles from both the donor and recipient. Molecular genetic analysis provided strong evidence that the tumor cells arose from the donor tissue.

Hamartomatous gastric polyposis in a patient with tuberous sclerosis

A 42-year-old female diagnosed with tuberous sclerosis was found to have multiple polyps in the fundus of stomach. On histologic examination, the lesions were hamartomatous polyps. In tuberous sclerosis, many lesions occur in multiple organs and there are several reports about the frequent association of hamartomatous polyps of the colon. However, gastric manifestation of tuberous sclerosis has not been established probably due to its asymptomatic nature. This is the first report of multiple gastric hamartomatous polyposis in patient with tuberous sclerosis.

Allelic loss at SMAD4 in polyps from juvenile polyposis patients and use of fluorescence in situ hybridization to demonstrate clonal origin of the epithelium

Juvenile polyposis syndrome (JPS; Online Mendelian Inheritance in Man2 174900) is a rare Mendelian disorder in which individuals have typical hamartomatous polyps within the gastrointestinal tract. The stromal element of the polyps has classically been thought to be the proliferative component, although epithelial malignancies (largely gastrointestinal cancers) occur more frequently than expected in JPS patients. Germ-line mutations in SMAD4 (DPC4) account for about a third of JPS cases. It has been postulated that the apparent paradox of a stromal lesion predisposing to epithelial malignancy can be resolved by the "landscaper" effect: an abnormal stromal environment affects the development of adjacent epithelial cells, and the resulting regeneration of damaged epithelium leads to an increased risk of cancer. We have found allele loss at the SMAD4 locus on 18q in polyps from JPS individuals with a germ-line SMAD4 mutation, showing that SMAD4 is acting as a tumor suppressor gene in JPS polyps, as it does in sporadic cancers of the gastrointestinal tract. Interphase fluorescence in situ hybridization showed deletion of one copy of SMAD4 in the epithelial component of JPS polyps, but not in the inflammatory infiltrate. Fluorescence in situ hybridization also suggested that a single copy of SMAD4 was present in stromal fibroblasts of JPS polyps. Thus, biallelic inactivation of SMAD4 occurs in both the epithelium and some of the stromal cells in these lesions, suggesting a common clonal origin. Epithelial malignancies almost certainly develop in juvenile polyposis through direct malignant progression of the epithelial component of the hamartomas. SMAD4/DPC4 probably acts as a "gatekeeper" tumor suppressor in juvenile polyps, and there is no need to invoke a "landscaper hypothesis."

Haploid loss of the tumor suppressor Smad4/Dpc4 initiates gastric polyposis and cancer in mice

The tumor suppressor SMAD4, also known as DPC4, deleted in pancreatic cancer, is a central mediator of TGF-beta signaling. It was previously shown that mice homozygous for a null mutation of Smad4 (Smad4-/-) died prior to gastrulation displaying impaired extraembryonic membrane formation and endoderm differentiation. Here we show that Smad4+/- mice began to develop polyposis in the fundus and antrum when they were over 6 - 12 months old, and in the duodenum and cecum in older animals at a lower frequency. With increasing age, polyps in the antrum show sequential changes from hyperplasia, to dysplasia, in-situ carcinoma, and finally invasion. These alterations are initiated by a dramatic expansion of the gastric epithelium where Smad4 is expressed. However, loss of the remaining Smad4 wild-type allele was detected only in later stages of tumor progression, suggesting that haploinsufficiency of Smad4 is sufficient for tumor initiation. Our data also showed that overexpression of TGF-beta1 and Cyclin D1 was associated with increased proliferation of gastric polyps and tumors. These studies demonstrate that Smad4 functions as a tumor suppressor in the gastrointestinal tract and also provide a valuable model for screening factors that promote or prevent gastric tumorigenesis.

[Hypertrophic and polypoid gastropathy associated with juvenile adenomatous polyposis coli]

Juvenile Polyposis is a syndrome with gastrointestinal polyps and increased cancer risk. The commonest form of this syndrome is inherited as autosomal dominant trait and presents as Familial Juvenile Polyposis Coli. Another variant involves mainly the stomach and another is generalized throughout the gastrointestinal tract. We present the case of two brothers with polyposis coli complicated by colonic cancer. The polyps were of juvenile, adenomatous and mixed types. The two patients after a decade of colonic endoscopic polypectomies presented gastric involvement by polyps and needed multiple endoscopic gastric resections. One brother underwent total gastrectomy. This stomach showed diffuse polyposis of hyperplastic and fundic gland types within an unexpected background of foveolar and glandular hypertrophic gastropathy. The patients at present are followed up with endoscopic procedures.

HMGI-C and HMGI(Y) immunoreactivity correlates with cytogenetic abnormalities in lipomas, pulmonary chondroid hamartomas, endometrial polyps, and uterine leiomyomas and is compatible with rearrangement of the HMGI-C and HMGI(Y) genes

High-mobility group (HMG) proteins are nonhistone nuclear proteins that play an important role in the regulation of chromatin structure and function. HMGI-C and HMGI(Y) are members of the HMGI family of HMG proteins, and their expression in adult tissues generally correlates with malignant tumor phenotypes. However, HMGI-C and HMGI(Y) dysregulation as a result of specific rearrangements involving 12q15 and 6p21, the respective chromosomal sites in which the HMGI-C and HMGI(Y) genes are located, is also identified in a variety of common benign mesenchymal tumors, such as lipomas and uterine leiomyomata. The general prevalence of HMGI-C and HMGI(Y) protein expression and its correlation with chromosomal alterations in these benign tumors are unknown. We analyzed 95 human tumors (20 lipomas, 21 pulmonary chondroid hamartomas, 26 uterine leiomyomata, and 28 endometrial polyps) representing a selection of the benign lesions in which karyotypic alterations involving the chromosomal regions 12q15 and 6p21 are frequently detected. All cases were successfully karyotyped and some of them analyzed by fluorescent in situ hybridization with probes spanning the HMGI-C and HMGI(Y) genes. The results of this study demonstrate that expression of HMGI-C or HMGI(Y) is a common occurrence in lipomas, pulmonary chondroid hamartomas, leiomyomata, and endometrial polyps; that it correlates with 12q15 and 6p21 chromosomal alterations (p < 0.001); and that it is compatible with rearrangement of the HMGI-C and HMGI(Y) genes. The expression pattern and cellular localization of the immunoreactivity support the view that in biphasic lesions composed of a mixture of both stromal and epithelial cells, such as pulmonary chondroid hamartoma and endometrial polyps, the mesenchymal component is the site of the HMGI genetic alterations.

Proliferative activity and cytometric characteristics in polyps of the nasal cavity and paranasal sinuses

Although several investigations have revealed the influence of cytokines, allergy, and environmental factors in polyp development, the etiology of nasal polyps is still unknown. To estimate the biology of this common disease the operative specimens of 50 patients who underwent surgery for polyps of the nasal cavity and the paranasal sinuses were examined; of these, 10 patients had recurrent disease and 23 patients had an allergy. The investigations included routine histology and quantitative DNA measurements, along with immunohistochemical identification of proliferation markers (i.e., MIB-1; proliferating cell nuclear antigen, PCNA). Histologically, most polyps revealed an infiltration with lymphocytes, eosinophilic granulocytes, and plasma cells. Twenty-five percent had a squamous metaplasia of the respiratory epithelium. Quantitative DNA analysis demonstrated diploid stemlines and lack of aneuploid cells with a DNA content exceeding 5c in most cases. Immunohistochemical detection of proliferation markers showed low proliferation rates in all cases. In 27 polyps no MIB-1 expression was detected, and in 7 polyps no PCNA expression was detected. The polyps of the 23 patients with proven allergic diathesis did not reveal higher scores for the parameters of DNA analysis (i.e., ploidy status and percentage of aneuploid cells) and proliferation scores. Nasal polyps of 10 patients with recurrent disease displayed higher scores for proliferation markers, and in five cases aneuploid cells with 5c exceeding rate (5cER) of 1.5-11.7% were detected. According to these results, polyps of the nasal cavity and paranasal sinuses showed low proliferation scores and were diploid. The data demonstrated that there was no increase of proliferation activity or ploidy shift toward aneuploidy in patients with allergy. Nevertheless, in recurrent disease some increase in proliferation activity and some changes in the parameters of the DNA analysis occurred, indicating more aggressive behavior of recurrent polyps in single cases.

Genetic testing and surgical decision making in hereditary colorectal cancer

Hereditary colorectal cancer results from specific genetic alterations. The causative genes for familial adenomatous polyposis, juvenile polyposis, Peutz-Jeghers syndrome, and hereditary nonpolyposis colorectal cancer have been cloned and characterized within the past decade. Genetic testing has therefore become more widely used to confirm the clinical diagnosis of each of those syndromes, to provide adequate surveillance, to allow screening of at-risk family members, and to help the surgeon in surgical decision making. The aim of this review is to analyze the importance of genetic testing in view of the clinical and surgical management of those gene-carriers individuals, and to discuss how should the surgeon integrate genetic testing in the evaluation of such patients.

Gastric and duodenal polyps in Smad4 (Dpc4) knockout mice

The SMAD4 (DPC4) gene was initially isolated as a candidate tumor suppressor from the convergent site of homozygous deletions on 18q in a panel of pancreatic carcinoma cell lines. It encodes a common cytoplasmic signaling molecule shared by the transforming growth factor-beta, activin, and bone morphogenic pathways. We recently inactivated its mouse homologue Smad4 and demonstrated its role in the malignant progression of benign adenomas to invasive adenocarcinomas by analyzing mice with Apc and Smad4 compound mutations. Although simple Smad4 homozygotes were embryonically lethal, the heterozygotes were fertile and appeared normal up to the age of 1 year. Upon further investigation, however, they have developed inflammatory polyps in the glandular stomach and duodenum. By PCR genotyping and immunohistochemical staining, the wild-type Smad4 allele has been lost in the polyp epithelial cells, ie., loss of heterozygosity. On the other hand, we have not found any mutations in such genes as K-Ras, H-Ras, N-Ras, p53, or PTEN. Histologically, the polyps are similar to human juvenile polyps showing moderate stromal cell proliferation and infiltrations by eosinophils and plasma cells. In addition, foci of adenocarcinoma with signet ring cells are also found. These results are consistent with a recent report that germ-line SMAD4 mutations are found in a subset of familial juvenile polyposis.

Polypoid dysplasias in ulcerative colitis and sporadic adenomas: genetic approach to the differential diagnosis (review)

Development of carcinoma in cases of ulcerative colitis is initiated out of regions of dysplasia. Dysplasia may present as single or multiple flat lesions, or as polypoid dysplasia (DALM-lesion). Dysplasia in DALM lesions may not be readily differentiated from that of sporadic adenomas by light microscopy. Such distinction, however, dictates therapeutic strategies. Since colectomy is treatment of choice in DALM lesions but removal of a sporadic adenoma is sufficient therapy, several attempts have been made to find markers to differentiate the two lesions. In recent years molecular genetic studies have demonstrated different genetic alterations in the dysplasia-carcinoma event in ulcerative colitis versus sporadic colorectal carcinoma, which may in fact help to differentiate the two entities. The diagnostic tools to differentiate DALM from sporadic adenomas are briefly described and a specific emphasis is given to the molecular genetic studies which may help in defining the specific entities.

Polypoid dysplasia in Barrett's esophagus: a clinicopathologic, immunohistochemical, and molecular study of five cases

Dysplasia in Barrett's esophagus (BE) is a precursor to adenocarcinoma and most commonly occurs as a flat, grossly undetectable lesion. Rarely, dysplasia in BE may grow as a polypoid lesion. Most BE-associated polypoid dysplastic lesions have been referred to as "adenomas" because of their histological similarity to a colonic adenoma. BE-associated polypoid dysplastic lesions have been less well characterized than the flat type. Therefore, our aim was to characterize the clinicopathologic and molecular features of five cases of BE-associated polypoid dysplasia and to review the literature on this entity. The cases were evaluated clinically, histologically, immunostained for MIB-1 and p53, and genotyped for loss of heterozygosity (LOH) at the adenomatous polyposis coli (APC) locus. Mucosal biopsy specimens of five BE patients without dysplasia, and five BE cases with high-grade flat dysplasia, were used as controls. The study patients were all male (average age, 71 years) who presented with symptoms of gastroesophageal reflux disease. Endoscopically, all five cases had a well-defined sessile or pedunculated polypoid lesion ranging from 0.4 to 1.5 cm in size in the mid (n = 1) or distal (n = 4) esophagus and were associated with specialized-type BE (four long segment, one short segment). Histologically, the polyps consisted of intestinalized epithelium with low- and high-grade dysplasia. All five cases contained adenocarcinoma (four within the polyp, one in adjacent BE). All polyps showed increased cell proliferation in the form of surface MiB-1 staining and showed positive p53 staining. Three of three (100%) informative cases showed LOH at the APC locus in the dysplastic epithelium and in areas of adenocarcinoma. All five flat dysplasia controls also showed surface MIB-1 staining and p53 positivity, and three of three informative controls showed LOH for APC. None of the nondysplastic BE controls showed any of these findings. Three patients were treated with esophagectomy and two with polypectomy. All were alive, without metastasis, from 2 months to 6 years later. A literature review of esophageal "adenomas" uncovered 12 cases. Four of these had no clinical or pathological information, two were, in fact, gastric heterotopic lesions, one was composed entirely of intestinal-type epithelium, and five were polypoid dysplastic lesions similar to the cases described here (three male, two female; mean age, 59 years). Four of these five cases were associated with adenocarcinoma in the polyp (two intramucosal, two submucosal). In summary, BE-associated polypoid dysplasia share similar clinical, pathological, and molecular features as flat dysplasia and are often associated with adenocarcinoma. Thus, we agree with other authors who recommend that the term adenoma, which usually carries a benign connotation, be abandoned in favor of a descriptive diagnostic term, such as "BE-associated polypoid dysplasia." BE patients with this lesion should be considered strong candidates for esophageal resection similar to lesions of this kind that occur in inflammatory bowel disease.

Heparin/heparan sulfate interacting protein gene expression is up-regulated in human colorectal carcinoma and correlated with differentiation status and metastasis

We applied a subtractive hybridization strategy to obtain genes that are differentially expressed in colorectal carcinoma. Heparin/heparan sulfate interacting protein (HIP) was shown to be up-regulated in colorectal carcinoma. A study of 53 patients with documented colorectal carcinoma showed that 70% of the tumors had HIP tumor-to-normal ratios (expression in tumor tissue compared to expression in normal mucosa) of >2. In six patients with concomitant polyps, HIP expression in the polyps was similar to the carcinoma, showing that up-regulation of HIP may be an early event in tumorigenesis. A significant inverse correlation between HIP levels and the presence of distant metastasis (Duke's stage D) was noted. Similarly, HIP expression was also related to differentiation status in human colorectal carcinoma cell lines. HIP expression was lower in the poorly differentiated COLO 205 cell line compared to the well-differentiated HT-29 cell line. The correlation was further strengthened by studies in COLO 205 cells that were induced to differentiate with herbimycin A treatment. HIP expression was significantly higher when the cells were induced to differentiate. Withdrawal of herbimycin A resulted in a reversal of morphological changes associated with differentiation and an associated decrease in HIP expression. These studies indicate that HIP is an important molecule for cell-cell and cell-extracellular matrix adhesion. The up-regulation of HIP may be an early event in tumorigenesis, and its increased expression may facilitate growth and local invasion. A lower expression of HIP in tumors results in decreased cell adhesion, favoring metastasis. HIP is a candidate marker of abnormal cell growth in the colon and a prognostic marker for colorectal carcinoma.

Characterisation of a subtype of colorectal cancer combining features of the suppressor and mild mutator pathways

BACKGROUND

10% of sporadic colorectal cancers are characterised by a low level of microsatellite instability (MSI-L). These are not thought to differ substantially from microsatelite-stable (MSS) cancers, but MSI-L and MSS cancers are distinguished clinicopathologically and in their spectrum of genetic alterations from cancers showing high level microsatellite instability (MSI-H).

AIMS

To study the distribution of molecular alterations in a series of colorectal cancers stratified by DNA microsatellite instability.

METHODS

A subset of an unselected series of colorectal cancers was grouped by the finding of DNA MSI at 0 loci (MSS) (n = 51), 1-2 loci (MSI-L) (n = 38) and 3-6 loci (MSI-H) (n = 25). The frequency of K-ras mutation, loss of heterozygosity (LOH) at 5q, 17p and 18q, and patterns of p53 and beta catenin immunohistochemistry was determined in the three groups.

RESULTS

MSI-H cancers had a low frequency of K-ras mutation (7%), LOH on chromosomes 5q (0%), 17p (0%) and 18q (12.5%), and a normal pattern of immunostaining for p53 and beta catenin. MSI-L cancers differed from MSS cancers in terms of a higher frequency of K-ras mutation (54% v 27%) (p = 0.01) and lower frequency of 5q LOH (23% v 48%) (p = 0.047). Whereas aberrant beta catenin expression and 5q LOH were concordant (both present or both absent) in 57% of MSS cancers, concordance was observed in only 20% of MSI-L cancers (p = 0.01).

CONCLUSIONS

MSI-L colorectal cancers are distinct from both MSI-H and MSS cancers. This subset combines features of the suppressor and mutator pathways, may be more dependent on K-ras than on the APC gene in the early stages of neoplastic evolution, and a proportion may be related histogenetically to the serrated (hyperplastic) polyp.

Genotype-phenotype correlations for the paranasal sinuses in cystic fibrosis

Genotype-phenotype correlations in cystic fibrosis (CF) have been found for lung and pancreatic function, but not for paranasal sinus disease. Because such correlations may have pathophysiological and clinical implications, the correlation of mutations, in particular DeltaF508, with paranasal sinus disease was investigated in 113 CF patients with known genotype. The clinical importance of paranasal sinus disease was evaluated using three parameters: polyps, overall clinical severity of upper airway problems, and surgery. Polyps were evaluated by nasal endoscopy and graded on a five-point scale. Four severity groups were distinguished based on history, clinical records, and examination: no upper airway problems; more problems than in control subjects; severe, recurrent or chronic problems; and paranasal sinus surgery cases. DeltaF508 homozygosity correlated with clinical severity (p < 0.02) and with the presence of polyps on endoscopy (p < 0.05). The relative risk for paranasal sinus surgery in DeltaF508 homozygous CF patients was 2.33. In conclusion, there are genotype-phenotype correlations for paranasal sinus disease in CF. DeltaF508 homozygosity is a risk factor for paranasal sinus disease in CF.

HMGIY is the target of 6p21.3 rearrangements in various benign mesenchymal tumors

Specific chromosomal abnormalities of chromosomal region 6p21.3 have been described in subsets of many benign mesenchymal tumors. In the presented study, we investigated a series of 36 such cases by FISH, and Southern blot analyses for HMGIY rearrangements. FISH results revealed that the chromosomal breakpoints of 11 pulmonary chondroid hamartomas (PCHs), 12 endometrial polyps (EPs), one lipoma, and two uterine leiomyomas (ULs) were located within a 80 kb region surrounding the HMGIY gene. In 11 PCHs and one UL the breakpoints were located 3' of HMGIY, and one PCH showed a breakpoint 5' of HMGIY. Southern blot analyses with intra- and extragenic probes were performed of primary tumor material or cell lines from one UL, three PCHs, and five EPs. In none of these cases was an intragenic rearrangement found. Finally, we were able to detect expression of truncated HMGIY transcripts by 3'-RACE PCR. Our data clearly show the role of a further member of the HMGI family in the development of benign mesenchymal tumors. Although most of the breakpoints of the chromosomal translocations involving HMGIY are located outside the gene, aberrant transcripts resembling the structure of those observed in the case of HMGIC have been found. Our molecular investigations thus led to the identification of the molecular mechanism by which rearrangements of either of two closely related genes lead to the development of frequent benign mesenchymal tumors in humans.

The usefulness of intra-operative endoscopy in Peutz-Jeghers syndrome: a case report

The Peutz-Jeghers syndrome is an autosomal dominant inherited disease manifested by a combination of mucocutaneous pigmentation and gastrointestinal hamartomatous polyps that usually cause intussusception and intestinal hemorrhage. We report a case in which the patient has been followed-up on for 14 years and who underwent surgical and endoscopic polyp removal several times as well as one intestinal resection. This time, with the use of combined surgery and perioperative endoscopy, 27 polyps were removed, performing only 3 enterotomies. This is the highest number in one session to be reported in the literature. The usefulness of this technique is providing a "clean small intestine" that allows the patient a longer time interval between laparotomies and reduces the complications associated with multiple laparotomies and resections.

Mutational abrogation of the PTEN/MMAC1 gene in gastrointestinal polyps in patients with Cowden disease

BACKGROUND & AIMS

To understand the molecular etiology of Cowden disease-associated gastrointestinal polyps, we analyzed the mutational status of PTEN/MMAC1, a recently identified Cowden disease gene located at 10q23, in gastric hamartomas, colonic adenoma, and juvenile polyps of 3 patients with Cowden disease.

METHODS

Messenger RNA expression, gene deletion, and sequence alteration of PTEN/MMAC1 were evaluated by quantitative polymerease chain reaction (PCR), PCR-single-strand conformation polymorphism, and sequencing analysis.

RESULTS

Germline missense mutation at codon 289 (AAA to GAA, Lys to Glu) and deletion of the wild-type allele were detected in the polyps of 2 patients with Cowden disease in the same family. Germline allelic deletion and transcriptional silencing of the remaining allele, probably caused by abnormal methylation, were also observed in a gastric hamartoma of 1 patient.

CONCLUSIONS

The germline mutation and alteration of the remaining allele observed in this study strongly support that PTEN/MMAC1 functions as a tumor suppressor in Cowden disease. This study is the first to show that the mutational abrogation of PTEN/MMAC1 plays a causal role in the genesis of gastrointestinal polyps in Cowden disease, providing molecular genetic evidence that colonic adenoma, juvenile polyp, and gastric hamartoma could be included in the manifestations of Cowden disease.