Differentiating large cell lymphoma from indolent small B-cell lymphoma in fine needle aspirates using p53, PCNA and transformed lymphocyte count

OBJECTIVE: To determine the usefulness of proliferating cell nuclear antigen (PCNA), p53 protein expression and transformed lymphocyte count (TLC) as adjunctive tests to differentiate indolent small B-cell lymphoma from large cell lymphoma in fine needle aspiration biopsies. STUDY DESIGN: Aspirates of lymphoproliferative disorders from April 1993 to January 1997 were reviewed. The percentage of TLCs was determined on the Papanicolaou smear. The percentage and intensity of p53 and PCNA immunocytochemical staining was evaluated on cell block sections. These results were compared and correlated with the final diagnoses based on available morphology, flow cytometry and clinical history. RESULTS: There were 40 cases of non-Hodgkin's lymphoma and 12 reactive lymph nodes. Adequate cell blocks were available on 16 large cell lymphomas, 7 grade 1-2 follicular center cell lymphomas, 6 mucosal associated lymphoid tissue lymphomas, 2 small lymphocytic lymphomas and 2 mantle cell lymphomas. Average TLC and p53 nuclear staining was highest in large cell lymphomas (57% TLC and 24% p53), followed by grades 1 and 2 follicular lymphomas (14% TLC and 15% p53) and lowest in other indolent lymphomas (< 10% TLC and < 1% p53). Average PCNA staining was highest in large cell lymphomas (46%) and lowest in small lymphocytic lymphomas (7%); however, TLC was the best parameter for differentiating large cell lymphoma from indolent small B-cell lymphoma. CONCLUSION: TLC differentiated large cell lymphoma from indolent small B-cell lymphoma better than either p53 or PCNA alone or in combination. Significant overlap between categories limits usefulness of these immunocytochemical stains for differentiating these entities.     

DNA ploidy in gastrointestinal B-cell lymphomas. An image analysis study of 43 cases

OBJECTIVE: To analyze the prognostic importance of DNA ploidy pattern on gastrointestinal (GI) B-cell lymphoma using image cytometry (ICM) and to compare the results with previously published flow cytometry (FCM) data. STUDY DESIGN: Forty-three cases of surgically resected primary GI B-cell lymphomas were examined. Thirty-eight tumors were located in the stomach, 2 in the small intestine, 1 in the large bowel and 2 in both the stomach and small intestine. Six cases were at stage E I 1, 15 at stage E I 2, 20 at stage E II 1 and 1 each at stages III and IV. Histologically, the lymphomas were classified as GI low grade marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) type (low grade, 12 cases), low grade MALT lymphoma with a high grade component (mixed type, 10 cases) and GI diffuse large B-cell lymphoma (DLBC) (high grade MALT lymphoma, 21 cases). After gross removal of nonneoplastic tissue, single cell suspensions were prepared from paraffin blocks and stained according to Feulgen. Ploidy analysis was done using a custom-made DNA cytometer and Optimas image analysis software (Optimas Corp., Seattle, Washington, U.S.A.). RESULTS: Aneuploidy was found in 42% (5/12 cases) of low grade MALT lymphoma, 90% (9/10 cases) of mixed type lymphoma and 100% (21/21 cases) of GI DLBCL. DNA ploidy had no significant impact on overall survival time (P = .73). CONCLUSION: ICM analysis showed a higher proportion of aneuploidy in GI lymphomas as compared to that in prior studies using FCM for ploidy determination. Whether DNA ploidy is an independent prognostic factor remains to be determined.     

Development of a Multiple-Locus Variable number of tandem repeat Analysis (MLVA) for Leptospira interrogans and its application to Leptospira interrogans serovar Australis isolates from Far North Queensland, Australia

The human gastric pathogen Helicobacter pylori causes chronic gastritis, peptic ulcer disease, gastric carcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma. It infects over 50% of the worlds' population, however, only a small subset of infected people experience H. pylori-associated illnesses. Associations with disease-specific factors remain enigmatic years after the genome sequences were deciphered. Infection with strains of Helicobacter pylori that carry the cytotoxin-associated antigen A (cagA) gene is associated with gastric carcinoma. Recent studies revealed mechanisms through which the cagA protein triggers oncopathogenic activities. Other candidate genes such as some members of the so-called plasticity region cluster are also implicated to be associated with carcinoma of stomach. Study of the evolution of polymorphisms and sequence variation in H. pylori populations on a global basis has provided a window into the history of human population migration and co-evolution of this pathogen with its host. Possible symbiotic relationships were debated since the discovery of this pathogen. The debate has been further intensified as some studies have posed the possibility that H. pylori infection may be beneficial in some humans. This assumption is based on increased incidence of gastro-oesophageal reflux disease (GERD), Barrett's oesophagus and adenocarcinoma of the oesophagus following H. pylori eradication in some countries. The contribution of comparative genomics to our understanding of the genome organisation and diversity of H. pylori and its pathophysiological importance to human healthcare is exemplified in this review.     

Gastric MALT lymphoma and Helicobacter pylori.

Primary gastric low-grade B-cell lymphomas are neoplastic mimics of mucosa associated lymphoid tissue (MALT) as exemplified by Peyer''s patches in the terminal ileum. Architectural and immunophenotypic properties of the neoplastic cells suggest that they originate from MALT-derived marginal zone B-cells. Paradoxically, the normal human stomach is devoid of organized MALT within which a lymphoma can develop. Lymphoid tissue is acquired in the stomach in response to antigenic stimulation, predominantly associated with Helicobacter pylori infection. Studies of patients with low-grade MALT lymphoma have confirmed a high incidence of H. pylori infection and suggest that the infection predates neoplastic transformation. Certain morphological features of MALT lymphomas suggest that the tumor cells remain responsive to antigen drive. Given the close association between gastric MALT lymphoma and H. pylori, it is possible that this organism provides such a drive. In vitro studies have shown that the tumor cells proliferate in a T-cell-dependent way to the presence of H. pylori. Several studies have now demonstrated that eradication of the organism in patients with low-grade gastric MALT lymphoma can result in regression of the tumor. In cases with a high-grade component, the associated low-grade part may regress, but most high-grade gastric MALT lymphomas are unresponsive to this conservative therapy.     

Overexpression of miR-142-5p and miR-155 in Gastric Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma Resistant to Helicobacter pylori Eradication

microRNAs (miRNAs) are small non-coding RNAs that can function as endogenous silencers of target genes and play critical roles in human malignancies. To investigate the molecular pathogenesis of gastric mucosa-associated lymphoid tissue (MALT) lymphoma, the miRNA expression profile was analyzed. miRNA microarray analysis with tissue specimens from gastric MALT lymphomas and surrounding non-tumor mucosae revealed that a hematopoietic-specific miRNA miR-142 and an oncogenic miRNA miR-155 were overexpressed in MALT lymphoma lesions. The expression levels of miR-142-5p and miR-155 were significantly increased in MALT lymphomas which do not respond to Helicobacter pylori (H. pylori) eradication. The expression levels of miR-142-5p and miR-155 were associated with the clinical courses of gastric MALT lymphoma cases. Overexpression of miR-142-5p and miR-155 was also observed in Helicobacter heilmannii-infected C57BL/6 mice, an animal model of gastric MALT lymphoma. In addition, miR-142-5p and miR-155 suppress the proapoptotic gene TP53INP1 as their target. The results of this study indicate that overexpression of miR-142-5p and miR-155 plays a critical role in the pathogenesis of gastric MALT lymphoma. These miRNAs might have potential application as therapeutic targets and novel biomarkers for gastric MALT lymphoma.     

Alfacalcidol as a modulator of growth of low grade non-Hodgkin's lymphomas.

Ten patients with low grade non-Hodgkin''s lymphoma (seven follicular small cleaved and three small lymphocytic) were treated with 1 microgram oral alfacalcidol (1 alpha-hydroxycholecalciferol) daily. Of the seven patients with lymphomas of follicular small cleaved subtype, one achieved complete and three partial remission, whereas none of three patients with small lymphocytic lymphomas responded. In seven of the 10 patients, 1,25(OH)2D3 receptors were measured in tissue from lymph nodes, and a positive correlation between the presence and amount of receptor and response to alfacalcidol was found. These preliminary data suggest that alfacalcidol has appreciable antitumour activity in low grade non-Hodgkin''s lymphomas.     

Helicobacter pylori infection‐induced H3Ser10 phosphorylation in stepwise gastric carcinogenesis and its clinical implications

Background

Our previous works have demonstrated that Helicobacter pylori (Hp) infection can alter histone H3 serine 10 phosphorylation status in gastric epithelial cells. However, whether Helicobacter pylori‐induced histone H3 serine 10 phosphorylation participates in gastric carcinogenesis is unknown. We investigate the expression of histone H3 serine 10 phosphorylation in various stages of gastric disease and explore its clinical implication.

Materials and Methods

Stomach biopsy samples from 129 patients were collected and stained with histone H3 serine 10 phosphorylation, Ki67, and Helicobacter pylori by immunohistochemistry staining, expressed as labeling index. They were categorized into nonatrophic gastritis, chronic atrophic gastritis, intestinal metaplasia, low‐grade intraepithelial neoplasia, high‐grade intraepithelial neoplasia, and intestinal‐type gastric cancer groups. Helicobacter pylori infection was determined by either ¹³C‐urea breath test or immunohistochemistry staining.

Results

In Helicobacter pylori‐negative patients, labeling index of histone H3 serine 10 phosphorylation was gradually increased in nonatrophic gastritis, chronic atrophic gastritis, intestinal metaplasia groups, peaked at low‐grade intraepithelial neoplasia, and declined in high‐grade intraepithelial neoplasia and gastric cancer groups. In Helicobacter pylori‐infected patients, labeling index of histone H3 serine 10 phosphorylation followed the similar pattern as above, with increased expression over the corresponding Helicobacter pylori‐negative controls except in nonatrophic gastritis patient whose labeling index was decreased when compared with Helicobacter pylori‐negative control. Labeling index of Ki67 in Helicobacter pylori‐negative groups was higher in gastric cancer than chronic atrophic gastritis and low‐grade intraepithelial neoplasia groups, and higher in intestinal metaplasia group compared with chronic atrophic gastritis group. In Helicobacter pylori‐positive groups, Ki67 labeling index was increased stepwise from nonatrophic gastritis to gastric cancer except slightly decrease in chronic atrophic gastritis group. In addition, we noted that histone H3 serine 10 phosphorylation staining is accompanied with its location changes from gastric gland bottom expanded to whole gland as disease stage progress.

Conclusions

These results indicate that stepwise gastric carcinogenesis is associated with altered histone H3 serine 10 phosphorylation, Helicobacter pylori infection enhances histone H3 serine 10 phosphorylation expression in these processes; it is also accompanied with histone H3 serine 10 phosphorylation location change from gland bottom staining expand to whole gland expression. The results suggest that epigenetic dysregulation may play important roles in Helicobacter pylori‐induced gastric cancer.     

Fine needle aspiration cytology of primary lymphoma of the thyroid: a report of 17 cases.

Between 1980 and 1998, 4272 thyroid surgical specimens with a preoperative fine needle aspirate were sent to our Anatomical Pathology Department. Among these cases there were 17 primary thyroid lymphomas, which constituted 0.3% of all the thyroid lesions and 2.3% of the thyroid malignancies. Seven cases were diffuse large B-cell (DLBC) lymphomas and 10 were MALT lymphomas. Of the DLBC lymphomas six were correctly diagnosed by fine needle aspiration cytology (FNAC) and one was diagnosed as positive for malignancy, and among MALT lymphomas four were diagnosed as lymphoma, four as suspicious for lymphoma, and three as Hashimoto's thyroiditis (HT). Our data indicate that the diagnosis of primary thyroid lymphoma of high grade is easy, and immunocytochemistry (ICC) can confirm suspicious cases. The diagnosis of MALT lymphoma is more difficult; ICC can confirm suspicious cases, and false-negative results seem to be caused by sampling error, because HT usually coexists with MALT lymphoma.     

抗CD20单克隆抗体治疗B 细胞淋巴瘤的效应机制

B细胞淋巴瘤是一种主要的非霍奇金淋巴瘤(non-Hodgkin’s lymphoma,NHL),95%以上的B细胞淋巴瘤均表达B细胞分化抗原CD20。尽管目前CD20在B细胞分化发育过程中的具体功能尚未阐明,但其特有的表达方式和在细胞膜上的分布特点决定了其成为B细胞淋巴瘤靶向治疗的主要靶点。近十年来,随着抗CD20单克隆抗体的不断发展和进步,联合传统的CHOP化疗方案,在NHL的治疗中显示出良好的效果。虽然,近年来抗CD20单抗逐渐被用于B细胞相关的自身免疫病的治疗,但相关作用机制尚不明确。在针对NHL的临床治疗中,抗CD20单抗的疗效被认为依赖于效应器机制,主要有ADCC、CDC和细胞凋亡。虽然抗CD20在淋巴瘤的治疗中具有显著的免疫疗效,但部分瘤荷较大的病人出现了耐药和复发,循环中大量B细胞由于单抗的结合而被机体的单核巨噬细胞吞噬或NK细胞杀伤,机体出现成熟B细胞空缺期,同时单核巨噬细胞、NK细胞和补体大量消耗,造成机体免疫效应功能饱和和效应器耗竭。本文就抗CD20单克隆抗体在治疗淋巴瘤中的具体作用机制及可能造成的机体效应器耗竭问题做一简要的概述。     

Immunohistochemical comparison of CD5, lambda,and kappa expression in primary and recurrent buccal Mucosa-associated lymphoid tissue (MALT) lymphomas

Mucosa-associated lymphoid tissue (MALT) lymphoma is a type of extranodal marginal zone B-cell lymphoma and is a distinct subtype of non-Hodgkin's lymphoma.Primary MALT lymphomas can also occur in the oral cavity, although their appearance in this location is rare. The neoplastic cells of which MALT lymphomas are composed express B-cell antigens and show monotypic immunoglobulin expression with light-chain restriction.Although neoplastic MALT lymphoma cells do not express CD5, previous studies have shown that CD5 positive MALT lymphomas are more prone to dissemination than those that do not express CD5. Moreover, there are some reports that describe kappa- and lambda- dual light chain expression in B cell malignant neoplasms.A 66-year-old Japanese woman with swelling of the right buccal mucosa was referred to our hospital. The lesion was excised and was pathologically diagnosed as a MALT lymphoma tumor with a t(11;18)(q21;q21) chromosome translocation.Swelling of the right buccal mucosa recurred 2 years later. The recurrent tumor was then excised and pathologically diagnosed as MALT lymphoma.Immunohistochemical examination of CD5, lambda, and kappa expressions revealed that the primary tumor was positive for CD5, kappa, and lambda, but the recurrent tumor was weakly positive for CD5 and kappa.With respect to lambda positivity, the recurrent tumor showed negativity.Our study suggests that immunohistochemical expression of CD5, kappa, and lambda in oral MALT lymphoma have the risk of recurrence.We first described the recurrence of CD5 positive MALT lymphoma in the oral cavity and compared the immunohistochemical expressions of CD5, lambda, and kappa between the primary and recurrent tumors.     

HDAC inhibitors potentiate the apoptotic effect of enzastaurin in lymphoma cells

Enzastaurin is an investigational PKCβ inhibitor that has growth inhibitory and pro-apoptotic effects in both B and T-cell lymphomas. We investigated the cytotoxicity and mechanisms of cell death of the combination of enzastaurin and low concentrations of histone deacetylase (HDAC) inhibitors in B-cell and T-cell lymphoma cell lines and primary lymphoma/leukemia cells. Combined enzastaurin/suberoylanilide hydroxamic acid treatment synergistically induced apoptosis in diffuse large B-cell lymphoma and T-cell lymphoma cell lines, and primary lymphoma/leukemia samples. Similarly, combined treatment of B-cell-like lymphoma cells with enzastaurin and two different HDAC inhibitors, valproic acid and (2E,4E)-6-(4-chlorophenylsulfanyl)-2,4-hexadienoic acid hydroxyamide synergistically induced apoptosis, suggesting the synergy is generalizable to other HDAC inhibitors. Our data indicate that enzastaurin/HDAC inhibitors therapy can synergistically inhibit growth and induce apoptosis in lymphoid malignancies and may be an effective therapeutic strategy. Potential mechanisms including enzastaurin mediated inhibition of HDAC inhibitor-induced compensatory survival pathways are discussed.     

The B cell antigen receptor and overexpression of MYC can cooperate in the genesis of B cell lymphomas

A variety of circumstantial evidence from humans has implicated the B cell antigen receptor (BCR) in the genesis of B cell lymphomas. We generated mouse models designed to test this possibility directly, and we found that both the constitutive and antigen-stimulated state of a clonal BCR affected the rate and outcome of lymphomagenesis initiated by the proto-oncogene MYC. The tumors that arose in the presence of constitutive BCR differed from those initiated by MYC alone and resembled chronic B cell lymphocytic leukemia/lymphoma (B-CLL), whereas those that arose in response to antigen stimulation resembled large B-cell lymphomas, particularly Burkitt lymphoma (BL). We linked the genesis of the BL-like tumors to antigen stimulus in three ways. First, in reconstruction experiments, stimulation of B cells by an autoantigen in the presence of overexpressed MYC gave rise to BL-like tumors that were, in turn, dependent on both MYC and the antigen for survival and proliferation. Second, genetic disruption of the pathway that mediates signaling from the BCR promptly killed cells of the BL-like tumors as well as the tumors resembling B-CLL. And third, growth of the murine BL could be inhibited by any of three distinctive immunosuppressants, in accord with the dependence of the tumors on antigen-induced signaling. Together, our results provide direct evidence that antigenic stimulation can participate in lymphomagenesis, point to a potential role for the constitutive BCR as well, and sustain the view that the constitutive BCR gives rise to signals different from those elicited by antigen. The mouse models described here should be useful in exploring further the pathogenesis of lymphomas, and in preclinical testing of new therapeutics.     

Small B cell lymphocytic lymphoma presenting as obstructive sleep apnea

Background  

Most lymphomas that involve the tonsil are large B cell lymphomas. Large B-cell lymphoma is a high grade malignancy which progresses rapidly. Tonsillar lymphoma usually presents as either a unilaterally enlarged palatine tonsil or as an ulcerative and fungating lesion over the tonsillar area. Small lymphocytic lymphomas (SLL) of the Waldeyer's ring are uncommon.     

Preoperative cytologic diagnosis of primary gastrointestinal malignant lymphoma

This report is based on the review and study of primary gastrointestinal malignant lymphomas as seen in cytologic brushing and washing specimens. During a period of 12 years (1970 to 1981), a total of 2,675 patients with malignant lymphoma involving the gastrointestinal tract were seen at Memorial Sloan-Kettering Cancer Center. Of these patients, 73 were diagnosed as having primary malignant lymphoma of the gastrointestinal tract. A total of 49 preoperative cytologic specimens obtained from 29 patients with histologically confirmed primary gastrointestinal malignant lymphoma were examined and are the basis for this study. Twenty-four patients had gastric primaries; three tumors were in the colon and two were small intestinal lymphomas. Thirty-three cytologic specimens taken from 25 patients were considered diagnostic for malignant lymphoma. A positive cytologic brushing was the only diagnostic preoperative specimen for 9 of the 29 patients. Combined cytologic and biopsy specimens provided a diagnosis of malignant lymphoma for 16 patients. Cytologic washings did not add to the diagnostic accuracy. The 29 cases of malignant lymphoma reviewed here were histologically subclassified as 23 large-cell, poorly differentiated and six small-cell, well-differentiated lesions. The cytomorphologic features of malignant lymphoma as observed in gastrointestinal specimens are outlined, and differential diagnoses are discussed. Clinicopathologic implications of the cytologic findings are considered.     

Increased apoptosis and angiogenesis in gastric low-grade mucosa-associated lymphoid tissue-type lymphoma by Helicobacter heilmannii infection in C57/BL6 mice

Helicobacter heilmannii has been reported to cause gastric low-grade mucosa-associated lymphoid tissue-type (MALT) lymphoma, but its precise pathophysiological mechanism remains to be clarified. We recently established a model of gastric B-cell MALT lymphoma in C57BL/6 mice by means of peroral infection of H. heilmannii primarily obtained from cynomolgus monkeys. Using this model, macroscopic, immunohistochemical, and electron microscopic observations of MALT lymphomas were carried out in order to examine the development of apoptosis and angiogenesis. Enhancement of the microvascular network and an increase in vascular endothelial growth factor-A were detected in the central region of the MALT lymphoma tissue in the infected mouse stomach, while vascular endothelial growth factor-C was detected at the margins of the MALT lymphomas. In addition, many H. heilmannii-invaded parietal cells showed caspase-3 immunoreactivity in the fundic mucosal tissue surrounding the MALT lymphoma. In conclusion, in H. heilmannii-induced MALT lymphoma, enhanced immunoreactivity of vascular endothelial growth factor-A and factor-C was observed in areas encircled by increased parietal cell apoptosis, which indicates the pathophysiological relevance of both angiogenesis and apoptosis in MALT lymphoma formation.     

P53 protein and Ki-67 expression in chronic gastritis patients with positive Helicobacter pylori infection

The present study was carried out to assess the predictive value and expression of the proliferative activity of Ki-67 and the expression of p53 protein in Helicobacter pylori associated chronic gastritis. This study comprised archival blocks from 20 dyspeptic patients who at National Hepatology and Tropical Medicine Research Institute underwent a diagnostic oesophago-gastroduodenoscopy with multiple gastric antral endoscopic biopsies for histological examination. The blocks were cut at 5 nM thicknesses, stained by hematoxylin and eosin to score the inflammatory grade and subjected to Giemsa stain to assess H. pylori infection, and then immune–histochemical method was done to determine protein P53 and Ki-67. The obtained results indicated that there was no significant association between the expression of Ki67 and P53 in the studied cases. There was no significant association between Ki67 and P53 in the presence of intestinal atrophy, intestinal metaplasia, intestinal activity and intestinal inflammation. While, there was significant association between Ki67 and P53 in intestinal dysplasia, P = 0.015, 0.025, respectively. It could be concluded that the significant association of the proliferative marker Ki-67 and apoptotic marker p53 protein with intestinal dysplasia may be one of the main predictive values in the development of gastric carcinoma in patients with gastritis secondary to H. pylori infection.     

Diagnosis of B-cell lymphoma. Utility of the polymerase chain reaction for detecting clonality from archival cytologic smears

OBJECTIVE: To apply the polymerase chain reaction (PCR) to detect clonality for potentially helping to establish a definitive diagnosis of lymphoma in cytologic material. STUDY DESIGN: In this retrospective study, Papanicolaou-stained cytologic smears and formalin-fixed, paraffin-embedded tissues from 17 cases of B-cell lymphoma were examined to investigate their clonality by a PCR technique using three different approaches (FR3, FR3A and FR2) for amplification of immunoglobulin heavy chain genes. Cytologic smears from 10 cases of nonneoplastic lymphoid tissues and T-cell lymphomas served as negative controls. RESULTS: Monoclonality was detected in 9 of 17 cases (53%) of B-cell lymphoma in cytologic smears as compared with 8 of 16 cases (50%) in tissue sections. Semi-nested PCRs (FR3A/FR2) were superior to the single PCR (FR3) in the detection rate (41% vs. 18%). Five of seven cases (71%) of marginal zone B-cell lymphomas showed monoclonality, whereas only 4 of 10 cases (40%) of diffuse large B-cell lymphomas did so. Monoclonality was demonstrated in none of the negative controls. CONCLUSIONS: Clonality detection in B-cell lymphomas by PCR using cytologic smears is specific and equal in sensitivity to that using formalin-fixed, paraffin-embedded tissues. The detection rate is especially excellent in marginal zone B-cell lymphoma, in which the cytologic diagnosis is particularly challenging. Combined seminested PCRs for FR3A and FR2 are advocated for a reliable assessment of clonality.     

Apport de la TEP/TDM au FDG en cancérologie de l’intestin grêle

This article focuses on the indication for FDG PET/CT in case of tumours of the small intestine, neuro-endocrine tumours excluded. The adenocarcinomas, lymphomas and sarcomas (including stromal tumours or GIST) are studied. There is no specific recommendation for FDG PET/CT in adenocarcinomas, extremely rare in comparison with colorectal adenocarcinomas. However, the utility of FDG PET/CT has been reported in clinical cases for detection and staging, especially in patients with high risk of developing the disease (Crohn's disease being the most important risk factor). The primary lymphomas of the small gut are also very rare, corresponding in all cases to non-Hodgkin lymphomas, for which the role of FDG PET/CT is recognised in follicular lymphoma, large B-cell lymphoma and Burkitt lymphoma. The stromal tumours correspond to the most frequent sarcomas. Stromal tumours in the small intestine are less frequent in the small intestine than in the stomach. The role of FDG PET/CT is well established in stromal tumours for the staging of the disease and for determining the efficacy of therapy with tyrosine kinase inhibitor. FDG PET is especially effective to evaluate the response since the radiologic criteria are difficult to assess, based not on the decrease of size of the lesions but on the decrease of density and of contrast enhance.     

A Changing Gastric Environment Leads to Adaptation of Lipopolysaccharide Variants in Helicobacter pylori Populations during Colonization

The human gastric pathogen Helicobacter pylori colonizes the stomachs of half of the human population, and causes development of peptic ulcer disease and gastric adenocarcinoma. H. pylori-associated chronic atrophic gastritis (ChAG) with loss of the acid-producing parietal cells, is correlated with an increased risk for development of gastric adenocarinoma. The majority of H. pylori isolates produce lipopolysaccharides (LPS) decorated with human-related Lewis epitopes, which have been shown to phase-vary in response to different environmental conditions. We have characterized the adaptations of H. pylori LPS and Lewis antigen expression to varying gastric conditions; in H. pylori isolates from mice with low or high gastric pH, respectively; in 482 clinical isolates from healthy individuals and from individuals with ChAG obtained at two time points with a four-year interval between endoscopies; and finally in isolates grown at different pH in vitro. Here we show that the gastric environment can contribute to a switch in Lewis phenotype in the two experimental mouse models. The clinical isolates from different human individuals showed that intra-individual isolates varied in Lewis antigen expression although the LPS diversity was relatively stable within each individual over time. Moreover, the isolates demonstrated considerable diversity in the levels of glycosylation and in the sizes of fucosylated O-antigen chains both within and between individuals. Thus our data suggest that different LPS variants exist in the colonizing H. pylori population, which can adapt to changes in the gastric environment and provide a means to regulate the inflammatory response of the host during disease progression.