IMMUNOCYTOCHEMICAL STUDY OF ENTEROCHROMAFFIN CELLS IN CARCINOMAS OF THE LARGE INTESTINE

In a series of 130 cases of adenocarcinomas of the large intestine, enterochromaffin (EC) cells were detected in 54 cases (41.3%) by limmunocytochemistry with anti-chromogranin monoclonal antibody. Among the 54 cases, 30 were found positive for serotonin, 14 for somatostatin, 11 for glucagon, 5 for pancreatic polypeptide, and only one for gastrin. The cases with EC cell (++) or polypeptide positive cells exhibited higher grade of differentiation, earlier stage of tumor extension and higher survival rate than those without EC cells. A significant difference of the EC cell population pattern among different histological grades of the tumors and non-neoplastic mucosa was found. The proportion of hormone, especially polypeptied positive cells was the highest in the mucosa and lowest in the moderately or poorly-differentiated carcinomas. The incidence, methodology and clinicopathological significance of EC cells found in the tumors are discussed.

Decreased expression of serotonin in the jejunum and increased numbers of mast cells in the terminal ileum in patients with irritable bowel syndrome

AIM: To investigate if there are changes in serotonin (5-HT) levels, enterochromaffin (EC) cells and mast cells in small intestinal mucosa of patients with irritable bowel syndrome (IBS). METHODS: Diarrhea-predominant (IBS-D, n = 20), or constipation-predominant (IBS-C, n = 18) IBS patients and healthy controls (n = 20) underwent colonoscopy and peroral small intestinal endoscopy, and mucosal samples were obtained at the descending part of the duodenum, proximal end of jejunum and terminal ileum. High-performance liquid chromatography- electrochemistry and immunohistochemical methods were used to detect 5-HT content, EC cells and mast cells. RESULTS: (1) There were no differences in the number and distribution of EC cells between IBS patients and the normal group. (2) The mucosal 5-HT contents at the duodenum, jejunum and ileum in IBS-C patients were 182 ± 90, 122 ± 54, 61 ± 35 ng/mg protein, respectively, which were all lower than those in the normal group (256 ± 84, 188 ± 91, and 93 ± 45 ng/ mg protein, respectively), with a significant difference at the jejunum (P < 0.05). There were no differences in the small intestinal mucosal 5-HT contents between IBS-D patients and the normal group. The mucosal 5-HT contents at the duodenum were significantly higher than those at the ileum in the three groups (P < 0.001). (3) The numbers of mast cells in patients with IBS-C and IBS-D at the ileum were 38.7 ± 9.4 and 35.8 ± 5.5/highpower field (hpf), respectively, which were significantly more than that in the normal group (29.8 ± 4.4/hpf) (P < 0.001). There was no significant difference in the numbers of mast cells at the other two parts between IBS patients and the normal group. The numbers of mast cells in IBS-C, IBS-D, and normal groups were all significantly higher at the ileum (38.7 ± 9.4, 35.8 ± 5.5, 29.8 ± 4.4/hpf, respectively) than at the duodenum (19.6 ± 4.7, 18.5 ± 6.3, 19.2 ± 3.3/hpf, respectively, P < 0.001). CONCLUSION: The changes in the 5-HT signaling pathway at the jejunum of IBS-C patients and the increase in mast cells in patients with IBS at the terminal ileum may offer evidence to explain the pathogenesis of IBS.

Midgut neuroendocrine tumor presenting with acute intestinal ischemia

Neuroendocrine tumors represent a heterogeneous group of neoplasms that arise from neuroendocrine cells and secrete various peptides and bioamines. While gastrointestinal neuroendocrine tumors,commonly called carcinoids,account for about 2/3 of all neuroendocrine tumors,they are relatively rare. Small intestine neuroendocrine tumors originate from intestinal enterochromaffin cells and represent about 1/4 of small intestine neoplasms. They can be asymptomatic or cause nonspecific symptoms,which usually leads to a delayed diagnosis. Imaging modalities can aid diagnosis and surgery remains the mainstay of treatment. We present a case of a jejunal neuroendocrine tumor that caused nonspecific symptoms for about 1 year before manifesting with acute mesenteric ischemia. Abdominal X-rays revealed pneumatosis intestinalis and an abdominal ultrasound and computed tomography confirmed the diagnosis. The patient was submitted to segmental enterectomy. Histopathological study demonstrated a neuroendocrine tumor with perineural and arterial infiltration and lymph node metastasis. The postoperative course was uneventful and the patient denied any adjuvant treatment.

Time to give up traditional methods for the management of gastrointestinal neuroendocrine tumours

Neuroendocrine tumors(NETs)are a rare and heterogeneous disease group and constitute 0.5%of all malignancies.The annual incidence of NETs is increasing worldwide.The reason for the increase in the incidence of NETs is the detection of benign lesions,incidental detection due to the highest use of endoscopic and imaging procedures,and higher recognition rates of pathologists.There have been exciting developments regarding NET biology in recent years.Among these,first of all,somatostatin receptors and downstream pathways in neuroendocrine cells have been found to be important regulatory mechanisms for protein synthesis,hormone secretion,and proliferation.Subsequently,activation of the mammalian target of rapamycin pathway was found to be an important mechanism in angiogenesis and tumor survival and cell metabolism.Finally,the importance of proangiogenic factors(platelet-derived growth factor,vascular endothelial growth factor,fibroblastic growth factor,angiopoietin,and semaphorins)in the progression of NET has been determined.Using the combination of biomarkers and imaging methods allows early evaluation of the appropriateness of treatment and response to treatment.