Carcinoid and other neuroendocrine tumors of the colon and rectum

Epidemiological, clinical and endoscopic characteristics of colorectal neuroendocrine neoplasms: a population-based study in the Netherlands

Background and study aims  Neuroendocrine neoplasms (NEN) account for a small number of colorectal neoplasms. Endoscopic detection is essential for diagnosis, treatment and follow-up. Little is known about incidence of NENs in colonoscopy populations or the relationship between clinical, endoscopic and histopathologic features. We evaluated epidemiology, endoscopic and clinical characteristics of colorectal NENs in a population-based cohort. Patients and methods  Medical records of NEN cases were cross-linked with the national pathology database from January 2001 to December 2015, in South Limburg County, the Netherlands, covering four endoscopy units. Senior pathologists reviewed and classified NENs using World Health Organization 5th edition (2019) guidelines. Results  The number of colorectal NEN diagnoses was stable over time with 0.6 NEN per 1,000 patients. A total of NENs were detected in 85 patients: 65 neuroendocrine tumors (NETs) and 20 poorly differentiated neuroendocrine carcinomas (NECs). Rectal NETs were usually small sessile/submucosal lesions with yellowish (lipoma-like) color. Colonic NETs were larger sessile/submucosal lesions with darker color compared to background. Colorectal NECs presented as large, dark-colored lesions with ulcerated/necrotizing areas. Conclusions  Our population-based data point to a stable and low incidence of 0.6 NEN per 1,000 patients in the Netherlands. Rectal NETs mainly present as small sessile yellowish lesions. Colonic NETs present as larger and darker lesions than background mucosa and NECs as darker lesions than background with ulceration/necrosis. Standardized endoscopic characterization of colorectal NENs is necessary to improve recognition of these lesions and provide a basis for evidence-based treatment and surveillance recommendations.

An update on the diagnosis of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) arise from neuroendocrine cells found throughout the gastrointestinal tract and islet cells of the pancreas. The incidence and prevalence of GEP-NENs have been increasing each year due to higher awareness, improved diagnostic modalities, and increased incidental detection on cross-sectional imaging and endoscopy for cancer screening and other conditions and symptoms. GEP-NENs are a heterogeneous group of tumors and have a wide range in clinical presentation, histopathologic features, and molecular biology. Clinical presentation most commonly depends on whether the GEP-NEN secretes an active hormone. The World Health Organization recently updated the classification of GEP-NENs to introduce a distinction between high-grade neuroendocrine tumors and neuroendocrine carcinomas, which can be identified using histology and molecular studies and are more aggressive with a worse prognosis compared to high-grade neuroendocrine tumors. As our understanding of the biology of GEP-NENs has grown, new and improved diagnostic modalities can be developed and optimized. Here, we discuss clinical features and updates in diagnosis, including histopathological analysis, biomarkers, molecular techniques, and radiology of GEP-NENs. We review established diagnostic tests and discuss promising novel diagnostic tests that are currently in development or require further investigation and validation prior to broad utilization in patient care.

Difficulty of predicting lymph node metastasis on CT in patients with rectal neuroendocrine tumors

Background

Surgical indications for rectal neuroendocrine tumors with potential lymph node metastasis remain controversial. Although accurate preoperative diagnosis of nodal status may be helpful for treatment strategy, scant data about clinical values of lymph node size have been reported. The aim of this retrospective study was to investigate the relationship between lymph node size and lymph node metastasis.

Methods

Participants comprised 102 patients who underwent rectal resection with total mesenteric excision or tumor-specific mesenteric excision and in some cases additional lateral pelvic lymph node dissection for rectal neuroendocrine tumor between June 2005 and September 2016. All lymph nodes from specimens were checked and measured.

Results

Pathological lymph node metastasis was confirmed in 37 patients (36%), including 6 patients (5.8%) with lateral pelvic lymph node metastasis. A total of 1169 lymph nodes in the mesorectum were retrieved from all specimens, with 78 lymph nodes (6.7%) showing metastasis. Mean length (long-axis diameter) of metastatic lymph nodes in the mesorectum was 4.31 mm, significantly larger than that of non-metastatic lymph nodes (2.39 mm, P<0.01). The optimal cut-off of major axis length for predicting mesorectal lymph node metastasis was 3 mm. We could predict lymph node metastasis in only 7 patients (21%) from preoperative multidetector-row computed tomography.

Conclusions

Metastatic lymph nodes were small, so predicting lymph node metastasis from preoperative computed tomography is difficult. Alternative modalities with a scan width less than 3 mm may be needed to predict lymph node metastasis of rectal NET with low cost and labour requirements.

Syndrome of inappropriate antidiuretic hormone associated with rectal small cell neuroendocrine carcinoma: a case report

Neuroendocrine tumors can arise from any portion of the gastrointestinal tract including the colon and rectum. In the scope of all colon and rectal malignancies, they are a rare cause of colorectal carcinoma. Relating to their pluripotent neuroendocrine cellular origins these carcinomas can produce a variety of biologically active peptides with several resultant paraneoplastic syndromes. One of these paraneoplastic syndromes is the syndrome of inappropriate antidiuretic hormone (SIADH). In the SIADH, supraphysiologic levels of vasopressin (antidiuretic hormone, AVP) precipitates exorbitant free water retention and resultant electrolyte abnormalities, most notably hyponatremia. Herein we report a rare case of paraneoplastic SIADH from rectal small cell neuroendocrine carcinoma. To our knowledge, SIADH from rectal small cell neuroendocrine carcinoma has been reported only three times.

Identification of immunotherapeutic targets by genomic profiling of rectal NET metastases

Neuroendocrine tumors (NETs) of the gastrointestinal tract are a rare and heterogeneous group of neoplasms with unique tumor biology and clinical management issues. While surgery is the only curative treatment option in patients with early stage NETs, the optimal management strategy for patients with advanced metastatic NETs is unknown. Based on the tremendous success of immunotherapeutic approaches, we sought to investigate such approaches in a case of metastatic rectal NET. Here, we apply an integrative approach using various computational and experimental methods to explore several aspects of the tumor-host immune interactions for immunotherapeutic options. Sequencing of six different liver metastases revealed a quite homogenous set of mutations, and further analysis of these mutations for immunogenicity revealed few neo-epitopes with pre-existing T cell reactivity, which can be used in therapeutic vaccines. Staining for immunomodulatory proteins and cytokine profiling showed that the immune setting is surprisingly different, when compared to liver metastases of colorectal cancer for instance. Taken together, our results highlight the broad range and complexity of tumor-host immune interaction and underline the value of an integrative approach.

Dilemmas in Endoscopic Management of Rectal Neuroendocrine Tumors: A Case-Based Discussion

Rectal neuroendocrine tumors are uncommon neoplasms that historically were regarded as having an indolent course. Due to the widespread use of screening colonoscopy neuroendocrine tumors of the rectum are identified with increasing frequency. More recent literature has suggested that rectal neuroendocrine tumors may progress in a more malignant fashion than previously believed. In this case-based discussion we present management dilemmas, analyze current guidelines, and highlight the role of endoscopic ultrasound, endoscopic resection, and surgery.

A case of very well-differentiated adenocarcinoma with carcinoid tumor in the ascending colon

Malignant tumors with mixed glandular and neuroendocrine characteristics with at least 30% of each component are classified as mixed adenoneuroendocrine carcinoma (MANEC) by the World Health Organization 2010 classification. We report here a case of very well-differentiated adenocarcinoma accompanied by carcinoid tumor, categorized as MANEC. A 41-year-old Japanese man was clinically diagnosed with ascending colon cancer and underwent right hemicolectomy. Using an immunohistologic technique, the pathologic diagnosis was very well-differentiated adenocarcinoma accompanied by carcinoid tumor and marked eosinophil infiltration, which was categorized as MANEC. By immunohistochemical analysis, tumor cells of the carcinoid component exhibited very low proliferation activity. Our case was thought to be MANEC without high malignant potential. MANEC as per the World Health Organization 2010 classification seems to include tumors with diverse grades of malignancy, and it might need to have subclassifications according to the malignancy potential of the tumor cells.

Four tumours including neuroendocrine tumour of the ileum

Gastroenteropancreatic neuroendocrine tumours are associated with development of further primary tumours. Certain conditions give an inherited predisposition to developing neoplasia. To the best of our knowledge, this is the first paper to report a patient with neuroendocrine tumour and three other tumours: a further bowel cancer, a brain tumour and a skin cancer. We report a case of a 42-year-old Caucasian man presenting with clinical features of intestinal obstruction who on histopathology of surgical specimen was found to have two distinct tumours of the bowel: a colonic adenocarcinoma at the splenic flexure and a well-differentiated neuroendocrine tumour of the terminal ileum. His history included a basal cell carcinoma and a benign brain tumour. He had extensive family history of neoplasia suggesting an inherited predisposition. Our case demonstrates the importance of investigating patients with known neuroendocrine tumours for further malignancy and suggests that patients with multiple primary malignancies should be referred for genetic testing.

[Appendiceal neuroendocrine tumor with lymph node metastasis in a teenager]

Neuroendocrine tumor (NET) is a cancer-like tumor that occurs mostly in the gastrointestinal system. Within the gastrointestinal tract, NET most commonly occurs in the rectum whereas appendix is very rarely involved. In most cases of appendiceal NET, it is found at a relatively early stage compared to other NETs because appendiceal NET frequently presents with acute appendicitis because appendiceal NET frequently presents with acute appendicitis even when the size is smaller than 1 cm. Therefore, it is very rare for lymph node metastasis to occur in a young adult. Herein, we report a rare case of grade 1 appendiceal NET with lymph node metastasis which developed in a teenage male.

The effect of preceding biopsy on complete endoscopic resection in rectal carcinoid tumor

Biopsy of rectal carcinoid tumor is commonly taken before endoscopic resection. However the preceding biopsy can inhibit complete resection by causing blurred tumor border and fibrosis of the tissue. The objective of the study was to investigate the effect of preceding biopsy on complete endoscopic resection in rectal carcinoid tumor. It was also determined if rectal carcinoid tumors can be macroscopically distinguished by endoscopy. We reviewed retrospectively the records of patients with rectal carcinoid tumor who had undergone an endoscopic treatment at our hospital, during a 7-yr period. The resection margin was clear in 57 of 98 cases. The preceding biopsy was taken in 57 cases and the biopsy was significantly associated with the risk of incomplete tumor resection (OR, 3.696; 95% CI, 1.528-8.938, P = 0.004). In 95.9% of the cases, it was possible to suspect a carcinoid tumor by macroscopic appearance during initial endoscopy. The preceding biopsy may disturb complete resection of rectal carcinoid tumor. In most cases, the carcinoid tumor could be suspected by macroscopic appearance. Therefore the preceding biopsy is not essential, and it may be avoided for the complete resection.

Asymptomatic primary rectal neuroendocrine carcinoma presented as a large pelvic mass

A 55-year-old healthy Thai man presented with incidental finding of a well-circumscribed, 5.8×5.4 cm mass in the right side of the pelvic cavity with heterogeneous density by a CT scan performed for trauma. No other distant lesion was detected. The pathology from pelvic mass showed poorly differentiated neuroendocrine carcinoma (NEC). A submucosal mass of 10 cm from the anal verge was found at colonoscopy, and a biopsy showed the same histopathology as in the pelvic mass. Final diagnosis was poorly differentiated primary rectal NEC with metastasis to the right iliac node (by CT scan). Carboplatin and etoposide were given for six cycles and tumour size was decreased.

Colonic and rectal NET's

Neuroendocrine tumours of the Colon and Rectum are rare but are increasing in incidence as a result of greater investigation with endoscopy and improved histological reporting. Classification with the 2010 WHO TNM staging system as well as grading based on the Ki-67 index has led to improved prognostic assessment. The use of Endoanal Ultrasound has increased the sensitivity of detection of depth of invasion and lymphovascular involvement, which is associated with a poor prognosis. Standard polypectomy has largely been replaced by endoscopic mucosal resection of smaller polyps, although newer techniques such as band ligation or endoscopic submucosal dissection are likely to be associated with less residual disease. The management of advanced disease remains a challenge but new treatments such as Peptide Receptor Targeted therapy and molecular targeted treatments offer hope of improved progression free survival in non-resectable disease.