Small intestinal neuroendocrine tumors (SI-NETs) originate from enterochromaffin cells scattered in the intestinal mucosa of the ileum and jejunum. Loss of one copy of chromosome 18 is the most frequent observed aberration in primary tumors and metastases. | Decrease of 5-hydroxymethylcytosine and TET1 with nuclear exclusion of TET2 in small intestinal neuroendocrine tumors