Neuroendocrine tumors including carcinoid tumors and pancreatic endocrine tumors are uncommon, and the genetic alterations in these indolent tumors are not well characterized. We studied global hypomethylation by analyzing long interspersed nucleotide elements (LINE)-1 and Alu methylation using pyrosequencing in 35 neuroendocrine tumors and corresponding normal tissue. The tumor samples were less methylated than normal tissue at LINE-1 (P ¼ 0.04) and Alu (P ¼ 0.001). The mean relative tumor hypomethylation (difference in methylation between normal tissue and in tumor) was 11.5710.0 for LINE-1 and 5.876.4 for Alu, and were correlated with each other (correlation coefficient 0.6, P ¼ 0.001). Relative tumor hypomethylation of LINE-1 was higher in ileal carcinoid tumors than in non-ileal carcinoid tumors and pancreatic endocrine tumors (P ¼ 0.047), and tumors with lymph node metastasis (P ¼ 0.02), chromosome 18 loss (P ¼ 0.001) and RAS-association domain family 1, isoform A gene methylation (P ¼ 0.02). Alu methylation in tumors was inversely correlated with methylation of O 6 -methyl-guanine methyltransferase gene (P ¼ 0.02). Our study shows that hypomethylation is more common in carcinoid tumors than in pancreatic endocrine tumors and is associated with clinicopathologic features, and genetic and epigenetic alterations in these tumors, including lymph node metastasis.

Endoscopic enucleation of gastric SETs originating in the muscularis propria layer was a safe and effective method for the histologic diagnosis and removal of small gastric SETs, especially those located in the cardia and the high body of the stomach.

Transabdominal US-guided pancreatic core biopsy may not provide enough tissue to evaluate characteristic histopathologic features of AIP that include LPSP or abundant IgG4-positive cell infiltration. The LPSP histology may be specific to AIP, but abundant IgG4-positive cells in the pancreas may not.