Mucosal Prolapse Polyp Mimicking Rectal Malignancy: A Case Report

Mucosal prolapse polyps (MPPs) are rare inflammatory lesions that are part of the mucosal prolapse syndrome. We present the case of a 40-year-old male with history of constipation referred to our institution with suspected rectal malignancy due to hematochezia and a palpable rectal mass. Colonoscopy revealed a 25 mm wide lesion suggestive of subepithelial origin but with marked erythema and erosion in the mucosa. Crypt dilatation and distortion, mixed inflammatory infiltrate and fibrosis were apparent on histological evaluation after bite-on-bite biopsies. Due to the initial suspicion of malignancy, resection was decided after discussion with the patient. However, due to non-elevation partial resection was performed allowing the diagnosis of MPP. Hematochezia ceased after obstipation treatment and endoscopic follow-up showed maintenance of the lesion with the same characteristics except for reduced dimension. MPP may mimic neoplastic lesions and should be considered in the differential diagnosis of rectal masses. History, endoscopy and histological characteristics are all necessary and important in the diagnosis of MPP.

Helicobacter pylori and microRNAs: Relation with innate immunity and progression of preneoplastic conditions

The accepted paradigm for intestinal-type gastric cancer pathogenesis is a multistep progression from chronic gastritis induced by Helicobacter pylori (H. pylori) to gastric atrophy, intestinal metaplasia, dysplasia and ultimately gastric cancer. The genetic and molecular mechanisms underlying disease progression are still not completely understood as only a fraction of colonized individuals ever develop neoplasia suggesting that bacterial, host and environmental factors are involved. MicroRNAs are noncoding RNAs that may influence H. pylori-related pathology through the regulation of the transcription and expression of various genes, playing an important role in inflammation, cell proliferation, apoptosis and differentiation. Indeed, H. pylori have been shown to modify microRNA expression in the gastric mucosa and microRNAs are involved in the immune host response to the bacteria and in the regulation of the inflammatory response. MicroRNAs have a key role in the regulation of inflammatory pathways and H. pylori may influence inflammation-mediated gastric carcinogenesis possibly through DNA methylation and epigenetic silencing of tumor suppressor microRNAs. Furthermore, microRNAs influenced by H. pylori also have been found to be involved in cell cycle regulation, apoptosis and epithelial-mesenchymal transition. Altogether, microRNAs seem to have an important role in the progression from gastritis to preneoplastic conditions and neoplastic lesions and since each microRNA can control the expression of hundreds to thousands of genes, knowledge of microRNAs target genes and their functions are of paramount importance. In this article we present a comprehensive review about the role of microRNAs in H. pylori gastric carcinogenesis, identifying the microRNAs downregulated and upregulated in the infection and clarifying their biological role in the link between immune host response, inflammation, DNA methylation and gastric carcinogenesis.