Appendiceal neuroendocrine tumors: Recent insights and clinical implications

Recurrent Ogilvie Syndrome as a Possible Manifestation of Alpha-Gal Syndrome (AGS) Requiring Surgical Management: A Case Report

We present a case of a male in his 60s with a history of alpha-gal syndrome (AGS) who presented with recurrent acute colonic pseudo-obstruction, also known as Ogilvie syndrome, and underwent surgical treatment for life-limiting symptoms of colonic distention, constipation, and abdominal pain. Prior to surgery, he was hospitalized multiple times after beef consumption and was diagnosed with Ogilvie syndrome, requiring a colonoscopy with rectal tube placement for symptom resolution. He later underwent a robotic subtotal colectomy with ileocolic anastomosis. Follow-up visits showed improvement in symptoms of constipation and abdominal distention. This case highlights that AGS may lead to severe manifestations, such as recurrent Ogilvie syndrome. Due to the increasing prevalence of AGS and limited data on disease course, further research is needed to determine symptom manifestations and the potential utility of surgery in management.

Two cases of dermatomyositis associated with neuroendocrine tumors

Dermatomyositis is an idiopathic inflammatory myopathy with cutaneous manifestations, which is associated with several types of malignancies, yet it has been rarely linked to neuroendocrine tumors (NETs). Here we report two cases of dermatomyositis associated with NETs of differing primary sites. Case 1: A 46-year-old female presented with a facial rash and proximal muscle weakness of both extremities. Investigations revealed elevated creatine kinase (CK) and positive anti-transcriptional intermediary factor 1-γ antibody (TIF1γ). The patient had been diagnosed with dermatomyositis and underwent a total body CT scan, which revealed prominent mediastinal lymphadenopathy, which a subsequent biopsy determined to be neuroendocrine carcinoma of small cell type. Treatment with high-dose corticosteroids was initiated, in addition to chemotherapy-based oncological management. Case 2: A 54-year-old female presented with a facial rash, progressive dyspnea, and general malaise. Laboratory investigations revealed positive anti-melanoma differentiation-associated gene-5 (MDA5) and positive anti-Ro antibody, with a normal level of creatine kinase (CK). A chest CT scan revealed multiple ground-glass opacities. Despite treatment with high-dose intravenous methylprednisolone, IVIG and an infusion of the anti-IL-6 sarilumab [Kevzara], the patient rapidly deteriorated and was intubated. Within days, the patient developed bowel ischemia and underwent a laparotomy which was then complicated by an invasive infection. This resulted in patient's death. Pathology results from colonic tissue demonstrated an appendiceal neuroendocrine tumor. These cases demonstrate the heterogeneity and complexity of dermatomyositis in association with neuroendocrine tumors.

Morphological and immunohistochemical features of neuroendocrine neoplasms in gastroenteropancreatic tract

BACKGROUND AND AIMS

Neuroendocrine neoplasms (NENs) result from neuroendocrine cell neoplastic proliferation, with both characteristics of endocrine and nerve cells. NENs arise in different localizations but the most common site is the gastrointestinal tract, including the pancreas. The morphology and frequency of NENs in our hospital were evaluated, as well as the correlation between lymph node status and Ki67 proliferative index.

MATERIALS AND METHODS

Retrospectively, we analyzed NEN pathohistological reports of patients who underwent surgical excision of gastroenteropancreatic tumors in the Clinical Center of Vojvodina in Novi Sad, from 2011 to 2018. The descriptive and correlation statistics were done. Chromogranin A, synaptophysin, CD56, and Ki67 were usually used as immunohistochemical markers.

RESULTS

The study registered 78 surgical specimens. The average age of patients was 58.88 (±17) years, whereby 53.8% were males. The most frequent site was the pancreas (29.5%), followed by the large intestine (26.9%). The mean tumor size was 3.71 (±3.13) cm. No significance was found in tumor differentiation degree (G1 = 32.1%, G2 = 26.9%, and G3 = 29.5%). Lymph node metastases were found in 47.44%. Positive correlation was found between the Ki67 index and the percentage of positive lymph nodes (r = 0.343, p = 0.046, p < 0.05, respectively). The correlation between tumor size and lymph node metastases revealed no significance in our study (r = 0.015, p = 0.480, p > 0.05, respectively).

CONCLUSION

Most NENs lymph node metastases originated from tumors with a high Ki67 index. The results confirm the use of proliferative index Ki67 as a prognostic marker for the presence of metastases, disease progression, and neuroendocrine tumor prognosis.

Management of Appendix Neuroendocrine Neoplasms: Insights on the Current Guidelines

Appendiceal neuroendocrine neoplasms (ANENs) usually present as incidental findings at the time of appendectomy for acute appendicitis. They are rare, accounting for only 0.5-1% of intestinal neoplasms; they are found in 0.3-0.9% of all appendectomy specimens. They are usually sporadic tumors. There are several histological types including well-differentiated neuroendocrine tumors (NETs), poorly differentiated neuroendocrine carcinomas (NECs), and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs). Histologic differentiation and the grade of well-differentiated NETs correlate with clinical behavior and prognosis. Management varies based on differentiation, aggressiveness, and metastatic potential. There is debate about the optimal surgical management for localized appendiceal NETs that are impacted by many factors including the tumor size, the extent of mesoappendiceal spread, lymphovascular invasion and perineural involvement. In addition, the data to guide therapy in metastatic disease are limited due to the paucity of these tumors. Here, we review the current advances in the management of ANENs within the context of a multidisciplinary approach to these tumors.

Appendiceal neoplasms and histological involvement of the mesoappendix: A case series

Introduction

Acute appendicitis is a common presentation to surgical departments, typically resulting in appendicectomy. Appendiceal tumours may not be visible intraoperatively, and are present in roughly 0.5–1% of specimens. Routine resection of the mesoappendix is not universally practiced, despite the mesoappendix being commonly involved in appendiceal tumours.

This is a case series of the histological findings of 21 patients with appendiceal tumours, with consideration to tumour within the resected mesoappendix.

Methods

We reviewed the histology of 1344 patients undergoing laparoscopic appendicectomy over a 6-year period assessing for the presence of appendiceal tumours and resected mesoappendix.

Results

Twenty-one patients were found to have appendiceal tumours, with a mean maximum tumour dimension of 7.2 mm. Sixteen of these patients had simultaneous mesoappendix resection, of whom six (38%) were found to have direct or indirect tumour tissue within the mesoappendix.

Conclusion

Further evidence for routine removal of the mesoappendix, and the need for larger prospective studies to investigate for any survival benefit. We note the worrying trend of conservative management of acute appendicitis.

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The mesoappendix is a key site of appendiceal tumour spread, directly & indirectly.

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Routine mesoappendix resection may reduce the need for reoperation.

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Conservative management of appendicitis may delay diagnosis of appendiceal tumours.

Sixty-One-Year-Old Female With Metastatic Poorly Differentiated Carcinoma of the Appendix With Omental Metastasis

Neuroendocrine tumors (NETs) are rare tumors that are often asymptomatic and were once considered benign. A specific subtype that we will dive into in this article is appendiceal neuroendocrine tumors (ANETS). ANETs are the most common tumors located within the appendix. Most often, they present as acute appendicitis and are found incidentally on pathology reports status post appendectomy. The objective of this article is to show that even though most of the ANETs are benign and fully treated via surgery, ANETs still have the potential to become malignant and metastasize. Our patient fits the common features seen in ANETS. She is a middle-aged woman with vague abdominal pain and no clear diagnosis on gastrointestinal (GI) workup. Computed tomography (CT) confirmed appendicitis, and pathology reports status post-surgery confirmed stage IV, pT4, Nx, M1 - poorly differentiated neuroendocrine carcinoma of the appendix with omental metastases.

Prognostic role of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in patients with midgut neuroendocrine tumors undergoing resective surgery

AIM

Several studies demonstrated the prognostic value of the neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and platelet-to-white blood cells ratio (PWR) in different types of tumors. However, there is no information about a possible role of NLR, PLR and PWR as predictor of presence of metastasis or multifocal disease in patients undergoing surgery with curative intent for midgut NET. The aim of our study was to test the role of preoperative NLR, PLR and PWR as predictors of patients undergoing surgery with curative intent for midgut NET.

METHODS

We retrospectively enrolled seven foregut, 35 midgut and six hindgut NET patients with gastrointestinal neuroendocrine tumors operated in our Units from January 2005 to June 2016. Details about preoperative laboratory data, surgical operation, histology and follow-up were retrieved. Non-parametric statistics, ROC curve analysis and survival analysis were used.

RESULTS

NLR was significantly higher in patients with distant metastasis (p = 0.04). The ROC curve analysis indicated that a threshold value of NLR of 2.6 predicted the presence of peritoneal metastasis with a specificity of 100% and a sensitivity of 71% and an overall accuracy of AUC = 0.81 (95%CI: 0.59-0.94), p = 0.05. PLR and PWR was not be associated to metastasis but tended to be associated to multifocal disease.

CONCLUSION

In patients with midgut NET, an impaired adaptive immune response, as suggested by a high NLR ratio, was associated to the presence of distant metastasis and in particular of peritoneal metastasis. This information may be helpful when planning the treatment of a patient with a midgut NET.

Lymphovascular Invasion Is Associated with Lymph Node Involvement in Small Appendiceal Neuroendocrine Tumors

BACKGROUND

Appendiceal neuroendocrine tumors (NETs) are incidentally found in up to 1% of appendectomy specimens. The association of lymphovascular invasion (LVI) with risk of regional lymph node involvement is unclear.

METHODS

From the National Cancer Database, 2004-2015, this study identified patients who had tumors 2 cm or smaller with one or more lymph nodes (LNs) pathologically evaluated. The histology was defined as typical, goblet cell, or composite NETs. Patient demographics, tumor characteristics, and treatment variables were analyzed.

RESULTS

The histologies for the 1767 identified patients were typical (n = 921, 52.1%), goblet cell (n = 556, 31.5%), and composite (n = 290, 16.4%). The tumor grades were low (70.4%), moderate (18.6%), and high (11%). The overall LN positivity was 17%. Of 1052 tumors evaluated, 215 (20.4%) had LVI. Overall survival decreased with node involvement (mean 84 vs. 124 months; p < 0.0001, log-rank). In the multivariate logistic regression analysis, LVI was independently associated with node involvement [odds ratio (OR) 5.0; p < 0.0001] after adjustment for patient age and tumor histologic subtype, size, and grade. In the subset analysis of typical NETs, tumor size of 1-2 cm (ref. < 1 cm; OR 5.5; p < 0.001) and presence of LVI (ref. absence of LVI; OR 4.8; p < 0.0001) were the only factors independently associated with LN involvement.

CONCLUSIONS

Node involvement is associated with worse overall survival in appendiceal NETs. The presence of LVI was strongly associated with lymph node involvement. An appendectomy specimen showing LVI should prompt strong consideration of colectomy with regional lymphadenectomy even for small, typical appendiceal NETs.

Incidental neuro-endocrine tumor of the appendix: Case report and literature review

INTRODUCTION

Neuroendocrine tumors (NETs) are neoplasms that arise from neuroendocrine cells that have properties of both neuronal and endocrine cells. NETs are most common in the small intestine, rectum, and the appendix and frequently termed carcinoid.

PRESENTATION OF CASE

A 30-year-old male presented with abdominal pain and tenderness in the RLQ. Computerized tomography revealed findings consistent with acute appendicitis. The patient underwent an uneventful laparoscopic appendectomy for an acutely inflamed appendicitis. Histopathological examination, showed a 0.5 cm well-differentiated neuroendocrine tumor of the distal appendix, with clear margins. The mitotic rate was <2 mitoses/10 high power field. Following guidelines, no further procedures were performed and follow-up one week later was uneventful.

DISCUSSION

Appendectomy for the treatment of appendiceal NETs smaller than 1 cm has been recommended as the treatment of these neoplasms by the guidelines set by The North American Neuroendocrine Society (NANETS). NANETS recommends right hemicolectomy for tumors originating at the base of the appendix, for tumors >2 cm in size, if there is evidence of lymphovascular or meso-appendiceal invasion, with mesenteric lymph node metastases, or for intermediate or high-grade tumors.

CONCLUSION

We present the case of a 30-year old male that presented with an appendiceal, well-differentiated NET that manifested as appendicitis and laparoscopic appendectomy was performed. The appendix was resected with clear margins. Given appropriate markers appendectomy can be curative.

Practice Patterns and Guideline Non-Adherence in Surgical Management of Appendiceal Carcinoid Tumors

BACKGROUND

Surgical management of appendiceal carcinoid tumors is heavily debated, despite National Comprehensive Cancer Network guidelines recommending aggressive resection of tumors >2 cm. We investigated national practice patterns and the predictors and impact of guideline non-adherence.

STUDY DESIGN

The National Cancer Database was queried for cases of appendiceal carcinoids diagnosed from 2004 to 2015 treated with either appendectomy or hemicolectomy. Multivariable logistic regression, adjusted for demographic and clinical factors, identified associations with the procedure type among patients stratified by tumor size ≤2 cm and >2 cm. Cox Proportional Hazards then identified associations with overall survival among stratified patient groups.

RESULTS

Of 3,198 cases of appendiceal carcinoids, 1,893 appendectomies and 1,305 hemicolectomies were identified. Contrary to National Comprehensive Cancer Network guidelines, 32.4% of tumors ≤2 cm were treated with hemicolectomy and 31.3% of tumors >2 cm were treated with definitive appendectomy. Hemicolectomy for small tumors was associated with age 65 years and older (odds ratio [OR] 2.4; 95% CI 1.7 to 3.3; reference group age 18 to 39 years), history of malignancy (OR 2.0; 95% CI 1.6 to 2.6), tumor size 1.1 to 2 cm (OR 2.8; 95% CI 2.3 to 3.4; reference group size ≤1 cm), and lymphovascular invasion (OR 2.2; 95% CI 1.6 to 3.2); appendectomy for large tumors was associated with age 65 years and older only (OR 2.2; 95% CI 1.1 to 4.2). Procedure type was not associated with survival for small or large tumors (hazard ratio 1.0; 95% CI 0.7 to 1.4 and hazard ratio 1.1; 95% CI 0.6 to 2.0, respectively).

CONCLUSIONS

Despite well-known size-based treatment guidelines for appendiceal carcinoids, one-third of patients in the US undergo hemicolectomy for small tumors and appendectomy for large tumors. Guideline non-adherence, however, is not associated with overall survival. Reasons for these practice patterns should be explored, and guidelines revisited.

A Multifocal Pattern of Neuroendocrine Neoplasms Along the Appendix: A Series of Six Cases

We present 6 cases with multifocal appendiceal neuroendocrine tumors, including their clinical and histopathological findings. To our knowledge, this is the first description of a multifocal pattern of a neuroendocrine neoplasm arising in the appendix. All patients presented in a setting requiring an acute appendectomy. The number of tumors ranged from 2 to 5. Histopathological examination revealed WHO (World Health Organization) grade 1 tumor in 3 patients and WHO grade 2 in the other 3 patients. The median duration of follow-up in these patients was 70 months (range = 6-192 months). No metastatic disease was observed. According to these findings, a multifocal pattern of neuroendocrine neoplasms along the appendix seems not to be a predictor for local advanced or metastatic disease.

Neuroendocrine tumor of the appendix-a case report and review of the literature

Incidental appendiceal neuroendocrine tumors (ANETs) occur in 0.2–0.7% of surgical resections for suspected appendicitis (Moris, Tsilimigras, Vagios, Ntanasis-stathopoulos, Karachaliou, Papalampros, et al. Neuroendocrine neoplasms of the appendix: a review of the literature. Anticancer Res [Internet]. 2018;38:601–11.). It’s a rare entity, clinically challenging and has controversy surrounding its management. A 69-year-old male presented to our clinic with acute right lower quadrant abdominal pain with less than 24 hours of evolution. The presumed clinical diagnosis was acute appendicitis. It was performed a laparoscopic appendectomy and the histopathologic result of the specimen showed neuroendocrine tumor of the appendix. ANETs are rare and typically diagnosed as incidental histopathologic finds in appendices specimens. However, they are the most common tumors arising from de appendix, between 30% and 80% of the cases (Pape, Niederle, Costa, Gross, Kelestimur, Kianmanesh, et al. ENETS consensus guidelines for neuroendocrine neoplasms of the appendix (excluding goblet cell carcinomas). Neuroendocrinology. 2016;103:144–52). Appendectomy may be sufficing for tumors <2 cm and they are associated with good long-term outcomes.

A well differentiated neuroendocrine tumor of the jejunum with peritoneal carcinomatosis: A case report

Neuroendocrine tumors (NETs), belong to a group of neoplasms that arise from neuroendocrine cells and express markers such as synaptophysin and chromogranin A. The digestive system (DS) is the most common site of NET development. The World Health Organization classification divides NETs into low grade (G1-G2) tumors (NETs) and high grade carcinomas [neuroendocrine carcinomas (NECs)], based on mitotic index and histological criteria. NET prognosis depends on tumor stage and grade. Low grade G1 NETs are characterized by a low proliferative rate and an indolent clinical course with a 5-year survival rate ranging between 38% (pancreas) and 88% (rectum). The present study reports a case of a low grade (G1) multifocal jejunal tumor with histologically confirmed features of aggressiveness, namely peritoneal carcinomatosis, lymph node metastasis and vascular carcinomatous emboli. Prediction of clinical behavior and survival in such a case is challenging. Although multiplicity and nodal metastases is not unusual for low grade NETs in this part of the gastrointestinal tract, peritoneal carcinomatosis is an extremely rare finding. Surgeons and histopathologists should be familiar with such eventualities and tumor boards are required in order to conclude whether aggressive therapeutic interventions may have any impact on patients' long term survival.

Curative and palliative surgery in patients with neuroendocrine tumors of the gastro-entero-pancreatic (GEP) tract

The incidence of neuroendocrine tumors (NET) increases with age. Lately, the diagnosis of NET was mainly caused by early detection of small NET (<1 cm) in the rectum and stomach, which are depicted by chance during routine and prophylactic endoscopy. Also in patients with large and metastatic pancreatic and intestinal tumors thorough pathologic investigation with use of different immunohistologic markers discovers more neuroendocrine tumors with low differentiation grade (G2-G3) and more neuroendocrine carcinomas (NEC), nowadays, than in former times. While gastric and rectal NET are discovered as small (<1 cm in diameter) and mainly highly differentiated tumors, demonstrating lymph node metastases in less than 10% of the patients, the majority of pancreatic and small bowel NET have already metastasized at the time of diagnosis. This is of clinical importance, since tumor stage and differentiation grade not only influence prognosis but also surgical procedure and may define whether a combination of surgery with systemic biologic therapy, chemotherapy or local cytoreductive procedures may be used. The indication for surgery and the preferred surgical procedure will have to consider personal risk factors of each patient (i.e. general health, additional illnesses, etc.) and tumor specific factors (i.e. tumor stage, grade of differentiation, functional activity, mass and variety of loco regional as well as distant metastases etc.). Together they define, whether radical curative or only palliative surgery can be applied. Altogether surgery is the only cure for locally advanced NET and helps to increase quality of life and overall survival in many patients with metastatic neuroendocrine tumors. The question of cure versus palliative therapy sometimes only can be answered with time, however. Many different aspects and various questions concerning the indication and extent of surgery and the best therapeutic procedure are still unanswered. Therefore, a close multidisciplinary cooperation of colleagues involved in biochemical and localization diagnostics and those active in various treatment areas is warranted to search for the optimal strategy in each individual patient. How far genetic screening impacts survival remains to be seen. Since surgeons do have a central role in the treatment of NET patients, they have to understand the need for integration into such an interdisciplinary team.

Flushing Disorders Associated with Gastrointestinal Symptoms: Part 1, Neuroendocrine Tumors, Mast Cell Disorders and Hyperbasophila

Flushing is the subjective sensation of warmth accompanied by visible cutaneous erythema occurring throughout the body with a predilection for the face, neck, pinnae, and upper trunk where the skin is thinnest and cutaneous vessels are superficially located and in greatest numbers. Flushing can be present in either a wet or dry form depending upon whether neural-mediated mechanisms are involved. Activation of the sympathetic nervous system results in wet flushing, accompanied by diaphoresis, due to concomitant stimulation of eccrine sweat glands. Wet flushing is caused by certain medications, panic disorder and paroxysmal extreme pain disorder (PEPD). Vasodilator mediated flushing due to the formation and release of a variety of biogenic amines, neuropeptides and phospholipid mediators such as histamine, serotonin and prostaglandins, respectively, typically presents as dry flushing where sweating is characteristically absent. Flushing occurring with neuroendocrine tumors accompanied by gastrointestinal symptoms is generally of the dry flushing variant, which may be an important clinical clue to the differential diagnosis. A number of primary diseases of the gastrointestinal tract cause flushing, and conversely extra-intestinal conditions are associated with flushing and gastrointestinal symptoms. Gastrointestinal findings vary and include one or more of the following non-specific symptoms such as abdominal pain, nausea, vomiting, diarrhea or constipation. The purpose of this review is to provide a focused comprehensive discussion on the presentation, pathophysiology, diagnostic evaluation and management of those diseases that arise from the gastrointestinal tract or other site that may cause gastrointestinal symptoms secondarily accompanied by flushing. This review is divided into two parts given the scope of conditions that cause flushing and affect the gastrointestinal tract: Part 1 covers neuroendocrine tumors (carcinoid, pheochromocytomas, vasoactive intestinal polypeptide, medullary carcinoma of the thyroid), polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes (POEMS), and conditions involving mast cells and basophils; while Part 2 covers dumping syndrome, mesenteric traction syndrome, rosacea, hyperthyroidism and thyroid storm, anaphylaxis, panic disorders, paroxysmal extreme pain disorder, and food, alcohol and medications.

Nothing But NET: A Review of Neuroendocrine Tumors and Carcinomas

This review covers the diverse topic of neuroendocrine neoplasms (NENs), a relatively rare and heterogeneous tumor type, comprising ~2% of all malignancies, with a prevalence of <200,000 in the United States, which makes it an orphan disease (Basu et al., 2010).1 For functional purposes, NENs are divided into two groups on the basis of clinical behavior, histology, and proliferation rate: well differentiated (low grade to intermediate grade) neuroendocrine tumors and poorly differentiated (high grade) neuroendocrine carcinoma (Bosman et al., 2010)2; this histological categorization/dichotomization is highly clinically relevant with respect to impact on treatment and prognosis even though it is not absolute since a subset of tumors with a low-grade appearance behaves similarly to high-grade lesions. Given the relative dearth of evidenced-based literature about this orphan disease as a whole (Modlin et al., 2008),3 since the focus of most articles is on particular anatomic subtypes of NENs (i.e., gastroenteropancreatic or pulmonary), the purpose of this review is to summarize the presentation, pathophysiology, staging, current standard of care treatments, and active areas of current research.

Multimodality Imaging Findings in Carcinoid Tumors: A Head-to-Toe Spectrum

Carcinoid tumors are a rare biologically heterogeneous group of neuroendocrine tumors with a spectrum ranging from benign indolent to aggressive metastatic tumors. They belong to the category of amine precursor uptake and decarboxylase tumors, or apudomas. The most common sites for primary locations are the gastrointestinal and respiratory tracts; however, any organ can be involved. The clinical presentation depends on location, aggressiveness, production of biologically active amines and peptides, paraneoplastic syndromes, and tendency for metastasis. Their reported age-adjusted incidence has increased in recent years, partly due to improved detection at radiologic imaging and endoscopy. Not a ll neuroendocrine cell tumors are carcinoids. Numerous systems have been proposed regarding their nomenclature and classification. Cross-sectional and functional imaging plays an important role in diagnosis, lesion characterization, and staging. Awareness of nomenclature, classification, common sites of involvement, and imaging presentation are pivotal for making the diagnosis. Knowledge of the diverse clinical, pathologic, and radiologic spectrum of carcinoid tumors involving various organs of the body is important for diagnosis and patient management. ^©RSNA, 2017.

Goblet cell carcinoid of the appendix and mixed adenoneuroendocrine carcinoma: Report of three cases

Neuroendocrine neoplasms are the most common epithelial tumors among appendix tumors. Appendix tumors that are completely or partially composed of neuroendocrine cells are divided into two categories: Classic carcinoid tumors and goblet cell carcinoid tumors (GCCT). They are known to progress more aggressively than classic (neuro) endocrine tumors. In this study, three cases with acute appendicitis symptoms are presented, including their clinical and histopathological findings. Microscopic examination detected GCCT in two cases and mixed adenoneuroendocrine carcinoma in one case, in addition to acute appendicitis.

The clinicopathological significance of angiogenesis in hindgut neuroendocrine tumors obtained via an endoscopic procedure

Background

As the World Health Organization grading system for gastroenteropancreatic-neuroendocrine tumors (GEP-NETs) may not always correlate with tumor progression, it is imperative that other independent predictors of tumor progression be established. To identify such predictors, we conducted a retrospective histopathological study of hindgut NETs, obtained from endoscopic procedures, and used statistical analyses to evaluate predictive factors.

Methods

We first obtained clinicopathological data of cases of hindgut NETs. Tissue sections from tumor samples were prepared and subjected to pathological examination. In particular, we calculated the microvessel density (MVD) and lymphatic microvessel density (LMVD) values, and performed appropriate statistical analyses.

Results

A total of 42 cases of hindgut NETs were selected for the study, 41 from the rectum and 1 from the sigmoid colon. Based on the Ki-67 labeling index, 34 cases were classified as NET G1 tumors and 8 as NET G2 tumors. MVD values ranged from 1.4/mm² to 73.9/mm² and LMVD values from 0/mm² to 22.9/mm². MVD and LMVD were identified as risk factors for venous and lymphatic invasion of hindgut NETs. Moreover, MVD positively correlated with the maximum diameter of the tumor.

Conclusions

Tumor progression of NETs may cause angiogenesis and lymphangiogenesis, via an unknown mechanism, as well as lymphovascular invasion. Angiogenesis likely plays an important role in occurrence and progression in the initial phase of hindgut NETs.