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Objetivo: realizar una revisión sistemática de los estudios que evalúan la prevalencia de H. pylori en los pacientes con linfoma MALT, así como analizar los factores de los que depende. Métodos: se efectuó una búsqueda bibliográfica en Pubmed seleccionando aquellos artículos en los que se estudiaba la prevalencia de H. pylori en pacientes con linfoma MALT. Resultados: se identificaron 38 estudios, incluyendo un total de 1.844 pacientes. La prevalencia media global de infección por H. pylori fue del 79%. En pacientes en los que se utilizaron 2 o más métodos para el diagnóstico de H. pylori la prevalencia fue del 85%, frente al 77% cuando se empleó un método diagnóstico (p < 0,0001). La prevalencia de H. pylori en pacientes diagnosticados mediante histología fue del 75 frente al 85% cuando se utilizó serología (p < 0,0001). La prevalencia de H. pylori en los linfomas MALT de alto grado fue del 60 frente al 79% en los de bajo grado (p < 0,0001). Se detectó la infección en el 74% de los linfomas MALT confinados a submucosa, y sólo en el 44% de aquellos que sobrepasaban la submucosa (p < 0,0001). Conclusiones: la prevalencia de la infección por H. pylori en pacientes con linfoma MALT gástrico parece depender del número y tipo de técnicas diagnósticas utilizadas para detectar la infección, del grado histológico y de la profundidad de la invasión tumoral. Si se utilizan los métodos diagnósticos adecuados y si se consideran únicamente los linfomas de bajo grado la prevalencia de infección por H. pylori es muy elevada, cercana al 90%.Objective: to perform a systematic review of studies evaluating H. pylori prevalence in patients with MALT lymphoma, and to analyze predictive factors of response. Methods: a literature search in Pubmed was performed of papers studying H. pylori prevalence in patients with MALT lymphoma. Results: 38 studies were identified including 1,844 patients. The average prevalence of H. pylori infection was 79%. In patients diagnosed with H. pylori infection using 2 or more methods prevalence was 85%, whereas it was 77% when only one diagnostic method was used (p < 0.0001). H. pylori prevalence in patients diagnosed by histology was 75%, whereas it was 85% when serology was used (p < 0.0001). H. pylori prevalence in high-grade lymphomas was 60%, and 79% in low-grade lymphomas (p < 0.0001). H. pylori infection was detected in 74% of lymphomas confined to the submucosa, but only in 44% of those reaching deeper beyond the submucosa (p < 0.0001). Conclusions: H. pylori prevalence in patients with MALT lymphoma is variable, and seems to depend, at least partly, on the number and type of diagnostic methods used, histologic grade, and deep tumor invasion. If appropriate diagnostic methods are used, and if only low-grade lymphomas are considered, H. pylori prevalence is high, nearly 90%, which reinforces the role of these bacteria in gastric MALT lymphoma.

Objective: to perform a retrospective review of the clinical characteristics and prevalence of H. pylori infection in patients with gastric MALT lymphoma diagnosed in our hospital during the last 15 years. Methods: patients with gastric MALT lymphoma diagnosed in our hospital during the last 15 years were retrospectively included. Demographic, clinic, analytic, endoscopic, and histological variables were reviewed. The extension study, the staging classification, and the presence of H. pylori infection were assessed. Results: thirty-seven patients with gastric MALT lymphoma were identified. Mean age was 61 years, with 62% of males. The most common presentation symptom was dyspepsia (76%), followed by digestive bleeding (11%) and constitutional syndrome (8%). At endoscopy, erosive lesions were identified in 41%, and proliferative or exophytic lesions in 43%. Most lymphomas were classified as low-grade (68%). The stage distribution was EI for 56%, EII for 13%, EIII for 3%, and EIV for 28%. The prevalence of H. pylori infection (histology in all cases, rapid urease test in 19%, and 13C-urea breath test in 24%) was 46%. When only low-grade lymphomas in stage EI were considered, H. pylori prevalence increased to 55%. When H. pylori infection was evaluated by 13C-urea breath testing (in addition to histology), the prevalence of H. pylori infection increased to 78%. Conclusions: it is probable that the reduced H. pylori prevalence found in some studies, as in ours, could be explained by false-negative results obtained when only one diagnostic method was used. Therefore, at least two (invasive) diagnostic methods should be performed. Furthermore, the performance of a non-invasive diagnostic method (such as a 13C-urea breath test) before the exclusion of H. pylori infection should be considered.Objetivo: revisar retrospectivamente las características clínicas y la prevalencia de infección por H. pylori en los pacientes con linfoma MALT gástrico diagnosticados en nuestro hospital durante los últimos 15 años. Métodos: se identificaron retrospectivamente todos los pacientes diagnosticados de linfoma MALT gástrico en nuestro centro en los últimos 15 años. Se revisaron las variables demográficas, clínicas, analíticas, endoscópicas, histológicas, el estudio de extensión, la estadificación y la infección por H. pylori. Resultados: se identificaron 37 pacientes con linfoma MALT gástrico, con una edad media de 61 años, el 62% varones. El síntoma de presentación más frecuente fue la dispepsia (76%), seguido de la hemorragia digestiva alta (11%) y el síndrome constitucional (8%). Durante la endoscopia se identificaron lesiones erosivas en el 41% y proliferativas/exofíticas en el 43%. La mayoría de los linfomas fueron de bajo grado (68%). Estadificación: EI (56%), EII (13%), EIII (3%) y EIV (28%). La prevalencia de H. pylori (histología en todos los casos, test rápido de la ureasa en el 19% y prueba del aliento con 13C-urea en el 24%) fue del 46%. Cuando únicamente se consideraron los linfomas de bajo grado en estadio EI, la prevalencia de H. pylori ascendió al 55%. Cuando la presencia de H. pylori se valoró mediante la prueba del aliento (además de la histología), la prevalencia de infección ascendió al 78%. Conclusiones: es probable que la reducida prevalencia de infección por H. pylori encontrada en algunos estudios, como el nuestro, sea debida a resultados falsos negativos obtenidos al utilizar un sólo test diagnóstico, por lo que se sugiere el empleo de al menos dos, e incluso añadir un método diagnóstico "no invasivo' como la prueba del aliento con 13C-urea antes de excluir definitivamente la infección por H. pylori.

Introduction and Objective: Follicular gastritis is associated with Helicobacter pylori infection, but little is known of its relation to bacterial genotypes. Our aim was to establish the relation between follicular gastritis and different H. pylori strains., Materials and Methods: An analytic case-control study was conducted that included 36 patients with follicular gastritis (cases) and 83 with nonatrophic gastritis (controls). The sociodemographic information was obtained through a questionnaire. Biopsies were evaluated according to the Sydney System and the Wotherspoon scoring system. Helicobacter pylori genotyping was performed using the polymerase chain reaction technique. The quantitative variables were presented as mean and standard deviation and the qualitative variables as proportions and absolute frequency. The effect of each variable on outcome (follicular gastritis) was evaluated through the odds ratio and its 95% confidence interval. Statistical significance was set at a P<0.05., Results: Follicular gastritis was associated with Helicobacter pylori infection (OR: 13.41, CI: 1.7-103, P=0.01). The CagA+ genotype was present in 56.5% of the cases and 58% of the controls. The cytotoxic VacAs1m1strain was present in 82% of the isolates in both groups. IceA1 frequency was 34.8% in the cases and 26% in the controls and the difference was not statistically significant., Conclusions: The population studied had elevated frequencies of cytotoxic Helicobacter pylori strains and the iceA1 genotype was more frequent in follicular gastritis., (Copyright © 2018 Asociación Mexicana de Gastroenterología. Publicado por Masson Doyma México S.A. All rights reserved.)