Endocrine tumors of the appendix: a pathologic review

Relation between WHO Classification and Location- and Functionality-Based Classifications of Neuroendocrine Neoplasms of the Digestive Tract

Practice of neuroendocrine neoplasms (NENs) of the digestive tract, which comprise of a highly diverse group of tumors with a rising incidence, faces multiple biological, diagnostic, and therapeutic issues. Part of these issues is due to misuse and misinterpretation of the classification and terminology of NENs of the digestive tract, which make it increasingly challenging to evaluate and compare the literature. For instance, grade 3 neuroendocrine tumors (NETs) are frequently referred to as neuroendocrine carcinomas (NECs) and vice versa, while NECs are, by definition, high grade and therefore constitute a separate entity from NETs. Moreover, the term NET is regularly misused to describe NENs in general, and NETs are frequently referred to as benign, while they should always be considered malignancies as they do have metastatic potential. To prevent misconceptions in future NEN-related research, we reviewed the most recent terminology used to classify NENs of the digestive tract and created an overview that combines the classification of these NENs according to the World Health Organization (WHO) with location- and functionality-based classifications. This overview may help clinicians and researchers in understanding the current literature and could serve as a guide in the clinic as well as for writing future studies on NENs of the digestive tract. In this way, we aim for the universal use of terminology, thereby providing an efficient foundation for future NEN-related research.

Analysis of surgical treatment of appendix neuroendocrine neoplasms-17 years of single-center experience

BACKGROUND/AIM

This study investigated the clinicopathological characteristics and treatment of appendix neuroendocrine neoplasms in appendectomy specimens of our center.

MATERIALS AND METHODS

The clinicopathological data, including age, sex, preoperative clinical manifestation, surgical method, and histopathological examination results of 11 patients with appendix neuroendocrine neoplasms confirmed by surgery and pathology between November 2005 and January 2023, were retrospectively analyzed.

RESULTS

In the histopathological examination of 7277 appendectomy specimens, 11 cases (0.2%) had appendix neuroendocrine neoplasms. Among the 11 patients, 8(72.7%) were males, and 3(27.3%) were females, with an average age of 48.1 years. All patients underwent emergency surgery. A total of 9 patients underwent open appendectomy, including 1 patient who underwent second-stage simple right hemicolectomy after an appendectomy, and two who underwent laparoscopic appendectomy. All 11 patients were followed up for a period of 1 to 17 years. All patients survived without any indication of tumor recurrence.

CONCLUSION

Appendiceal neuroendocrine neoplasms are low-grade malignant tumors originating from neuroendocrine cells. They are rarely seen in clinical practice and are often treated based on acute and chronic appendicitis symptoms. These tumors are challenging to diagnose before surgery due to the lack of specificity in clinical manifestations and auxiliary examinations. The diagnosis generally depends on postoperative pathology and immunohistochemistry. Despite the diagnostic challenges, these tumors have a favorable prognosis.

An unusual case of appendicitis due to appendiceal neuroendocrine tumor in a patient: A case report

Appendiceal neuroendocrine tumor (NET) is the most common type of appendiceal cancer and is rare in the pediatric population. The clinical characteristics of this cancer are not specific and are highly similar to those of acute appendicitis. By contrast, acute appendicitis is a common surgical indication that is caused by obstruction of the appendix lumen. With a detection rate of 0.5-1% in all appendectomy specimens, appendiceal NET is rare histopathologically and can easily be missed. However, detecting an appendiceal NET in a patient with appendicitis is highly difficult. Therefore, clinicians must be aware of this much under-reported and rare tumor in children. In the present report, a case was reported, of a 13-year-old female child who initially presented with clinical presentation of acute appendicitis, but was subsequently diagnosed with appendiceal NET by histopathological examination after an emergency appendectomy. Follow-up examination including abdominal enhanced CT and enteroscopy 2 years after surgery revealed normal results.

Lessons learned about appendiceal neuroendocrine neoplasms from data analysis of the Belgian Cancer Registry 2010-2015

BACKGROUND AND STUDY AIMS

Appendiceal neuroendocrine neo-plasms (aNENs) are a diverse group of malignant neoplasms of varying biological behavior for which information about manage-ment and outcome is sparse, with the majority of available studies being retrospective, including only a limited number of patients, and therefore not necessarily reflecting the reality in the community. In the present study clinical, epidemiological and pathological data of appendiceal neuroendocrine neoplasms in Belgium is provided and compared with current literature.

METHODS

A population-based study was conducted by linking data of the Belgian Cancer Registry with medical procedures in the Belgian Health Insurance database for patients diagnosed with aNEN between 2010 and 2015.

RESULTS

We found an aNEN incidence of 0.97/100.000 person years in Belgium. Neuroendocrine carcinoma of the appendix are rare. Most appendiceal neuroendocrine tumors (aNETs) are small G1 tumors. Positive lymph nodes are often found in tumors larger than 2cm, especially aNET G2.

CONCLUSION

A rapid uptake of changing classifications was seen in the community. However, systematic reporting of risk factors for small aNEN can still be improved and should be stimulated. In 9% of cases, reclassifications had to be made, pointing out that in a retrospective analysis, original pathological reports should be checked for specific parameters, before reliable conclusions can be drawn.

Radical surgical treatment of neuroendocrine tumors of the appendix in children - a Polish multicenter study

INTRODUCTION

The aim of the study was to examine management of pediatric appendiceal neuroendocrine tumors (ANETs) in Poland.

METHODS

Records of 27 patients with ANET diagnosed incidentally after appendectomy in the last decade.

RESULTS

Well-differentiated NET G1/G2 was diagnosed in 25 and well-differentiated neuroendocrine carcinoma G3 in 2 patients. Extended surgery was performed primarily in one instance and secondarily in 10 patients (right hemicolectomy in 9, ileocecal resection in 1) without adjuvant chemotherapy. Follow-up range was 1-121 months. Recurrence after secondary surgery was observed in 1 (3.7%) patient.

CONCLUSIONS

Applying ENETS guidelines resulted in 100% overall survival of patients with NET.

Lights and darks of neuroendocrine tumors of the appendix

INTRODUCTION

Neuroendocrine tumors of the appendix are a relatively frequent type of neuroendocrine tumor, usually detected incidentally after appendectomy. Almost all small slow-growing G1 tumors with no risk factors are cured with appendectomy while the rare and aggressive G3 carcinomas may represent a challenge in terms of management and often lead to a poor outcome. In the middle of the spectrum, a number of tumors present with in-between features and sometimes no clear-cut guidance emerges from the literature for directing the management and follow-up of these patients.

EVIDENCE ACQUISITION

A meticulous review of the literature on neuroendocrine tumors of the appendix, including the recommendations published by the relevant international societies.

EVIDENCE SYNTHESIS

The literature on the neuroendocrine tumors of the appendix appears to be inhomogeneous. Likely this occurs as a consequence of a number of factors, including the mostly retrospective nature of the available data, the heterogeneous records of the same, and some peculiar aspects of the appendiceal neuroendocrine tumors, with evidence of considerable biological and clinical differences in terms of epidemiology, management, and prognosis from the less aggressive tumors to the most aggressive cancers. In particular, some situations concerning tumors in the middle of the biological and clinical spectrum are still poorly defined.

CONCLUSIONS

There are some persisting "grey areas" with regard to the characterization and the clinical management of neuroendocrine tumors of the appendix. An increasing awareness of the biological and clinical aspects of this disease and new, ideally prospective, focused studies might help and clarify some relevant issues that are not fully elucidated yet and could increase the solidity of the guidance for the management and the follow-up of the patients.

Clinicopathologic and prognostic features in appendiceal malignancies: does tumor invasiveness matter?

Objectives

To evaluate the survival rates of appendiceal tumors and prognostic factors affecting survival.

Material and Methods

Demographic features, tumor characteristics and pre- and post-operative outcomes of the patients were analyzed retrospectively. The study was performed according to the Helsinki declaration.

Results

Twenty-three of the 2840 specimens were investigated prospectively. Median age of the patients was 28 (range: 1-89) years, with a male (n= 1730, 60.9%) to female (n= 1110, 39.1%) ratio of 1.55. Pediatric group did not present appendiceal malignancy. Carcinoid tumors were reported in 17 (0.59%) and adenocarcinoma was reported in 6 (0.20%) patients. Multivariate analyses of the subtypes showed serosal invasion as an independent risk factor for mucinous and non-mucinous adenocarcinoma (HR: -2.70, 95% CI: 0.006-0.755, p= 0.029). Median follow-up time was 48 months (range: 28-61 months) and disease specific survival rates of carcinoid tumors, mucinous- and non-mucinous adenocarcinomas were 36(95% CI 32-40), 30 (95% CI 13-46), 43 (95% CI 30-55) months, respectively (p= 0.749). Factors affecting survival in the univariate analyses were advanced tumor stage, serosal invasion and tumor invasion depth. In multivariate analyses, tumor invasion depth was the only independent prognostic factor with poor survival rates in all subtypes of appendiceal malignancies (HR= 1.31 (95% CI: 1.01-13.5), p= 0.047).

Conclusion

Tumor subtype and tumor invasiveness are important risk factors for survival. Besides other treatment modalities, appendectomy still remains the survival benefit with better clinical outcomes.

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.

Genetics and Epigenetics of Gastroenteropancreatic Neuroendocrine Neoplasms

Gastroenteropancreatic (GEP) neuroendocrine neoplasms (NENs) are heterogeneous regarding site of origin, biological behavior, and malignant potential. There has been a rapid increase in data publication during the last 10 years, mainly driven by high-throughput studies on pancreatic and small intestinal neuroendocrine tumors (NETs). This review summarizes the present knowledge on genetic and epigenetic alterations. We integrated the available information from each compartment to give a pathway-based overview. This provided a summary of the critical alterations sustaining neoplastic cells. It also highlighted similarities and differences across anatomical locations and points that need further investigation. GEP-NENs include well-differentiated NETs and poorly differentiated neuroendocrine carcinomas (NECs). NENs are graded as G1, G2, or G3 based on mitotic count and/or Ki-67 labeling index, NECs are G3 by definition. The distinction between NETs and NECs is also linked to their genetic background, as TP53 and RB1 inactivation in NECs set them apart from NETs. A large number of genetic and epigenetic alterations have been reported. Recurrent changes have been traced back to a reduced number of core pathways, including DNA damage repair, cell cycle regulation, and phosphatidylinositol 3-kinase/mammalian target of rapamycin signaling. In pancreatic tumors, chromatin remodeling/histone methylation and telomere alteration are also affected. However, also owing to the paucity of disease models, further research is necessary to fully integrate and functionalize data on deregulated pathways to recapitulate the large heterogeneity of behaviors displayed by these tumors. This is expected to impact diagnostics, prognostic stratification, and planning of personalized therapy.

Recent Updates on Neuroendocrine Tumors From the Gastrointestinal and Pancreatobiliary Tracts

CONTEXT

-Gastrointestinal (GI) and pancreatobiliary tracts contain a variety of neuroendocrine cells that constitute a diffuse endocrine system. Neuroendocrine tumors (NETs) from these organs are heterogeneous tumors with diverse clinical behaviors. Recent improvements in the understanding of NETs from the GI and pancreatobiliary tracts have led to more-refined definitions of the clinicopathologic characteristics of these tumors. Under the 2010 World Health Organization classification scheme, NETs are classified as grade (G) 1 NETs, G2 NETs, neuroendocrine carcinomas, and mixed adenoneuroendocrine carcinomas. Histologic grades are dependent on mitotic counts and the Ki-67 labeling index. Several new issues arose after implementation of the 2010 World Health Organization classification scheme, such as issues with well-differentiated NETs with G3 Ki-67 labeling index and the evaluation of mitotic counts and Ki-67 labeling. Hereditary syndromes, including multiple endocrine neoplasia type 1 syndrome, von Hippel-Lindau syndrome, neurofibromatosis 1, and tuberous sclerosis, are related to NETs of the GI and pancreatobiliary tracts. Several prognostic markers of GI and pancreatobiliary tract NETs have been introduced, but many of them require further validation.

OBJECTIVE

-To understand clinicopathologic characteristics of NETs from the GI and pancreatobiliary tracts.

DATA SOURCES

-PubMed (US National Library of Medicine) reports were reviewed.

CONCLUSIONS

-In this review, we briefly summarize recent developments and issues related to NETs of the GI and pancreatobiliary tracts.

An Unusual Case of Appendiceal Carcinoid Tumor in a Child- Case Report

Carcinoid tumors of the appendix are rare in children. They clinically present with features of acute appendicitis and are often diagnosed incidentally on the resected specimens. Local disease carries an excellent prognosis and simple appendicectomy suffices, whereas advanced cases need a right hemicolectomy. Clinicians must be aware of this under reported and rare tumor in chidren. We report a case of appendiceal carcinoid tumor in a 10 year old male child who presented with clinical features of acute appendicitis which was diagnosed on histopathological examination.

Incidental neuroendocrine tumor of the appendiceal base less than20 mm in diameter: is appendectomy enough?

The appendixis the second primary site for neuroendocrine tumors. The management of incidentelly discovered neuroendocrine tumor of the appendiceal base less than 20 mm in diameter is still controversal. The aim of this study was to discuss the management of such tumors. Three patients were operated on for acute appendicitis. Histopathologic examination of surgery specimens revealed neuroendocrine tumors of the appendiceal base less than 20 mm in diameter. Since no one presented with poor prognostic factors, no complementary right hemicolectomy was performed. No recurrence was observed. The existence of poorprognostic factors at histopathologic examination should indicate complementary right hemicolectomy for incidental neuroendocrine tumor of the appendiceal base less than 20 mm in diameter.

Carcinoid tumours of the appendix in children having appendicectomies at Princess Margaret Hospital since 1995

AIM

The diagnosis of carcinoid tumour is a relatively rare one. Our surgical approach has changed over the last two decades from predominantly open to predominately laparoscopic with a tendency to leave the mesoappendix in situ. The aim of this audit was to identify how many cases we had at PMH and to see whether the shift in surgical approach allowed us to make prognostic decisions in keeping with current best practice and whether this made any difference in further surgery requirements or outcome for patients.

METHODS

A retrospective review of all cases of carcinoid identified in our search of all appendicectomy histopathology results was conducted. Results were compared to those found in other studies. Duration of follow up and further investigations was reviewed, as was whether or not there was any recurrence.

RESULTS

Our incidence of carcinoid tumours in patients undergoing appendicectomy since 1995 was 0.35%, similar to that in other centres. None of our patients had surgery beyond an appendicectomy and our active follow up varied from none to 6 months. There were no recurrences in this time.

CONCLUSIONS

The literature review carried out suggests further meta-analysis is needed including data on long term follow up before definitive guidelines regarding extent of surgical treatment and follow up based on histopathology are created. The condition is rare and the studies small, resulting in no clear consensus on the best practice for tumours measuring between 1 and 1.5 cm in diameter. Our surgical approach to appendicectomies has changed; it is unclear whether this has resulted in a change in outcome.

Tumor staging but not grading is associated with adverse clinical outcome in neuroendocrine tumors of the appendix: a retrospective clinical pathologic analysis of 138 cases

Appendiceal neuroendocrine neoplasms (NENs) are rare and usually incidentally discovered. Most cases are clinically indolent, although the rare aggressive ones are poorly predictable. The aim of this study was to test the applicability and prognostic significance of the new World Health Organization (WHO) classification and to test the several pathologic features and TNM staging systems (American Joint Committee on Cancer and European Neuroendocrine Tumor Society) in these tumors. A multi-institutional retrospective series of 138 appendiceal NENs was selected on the basis of the availability of both pathologic material and clinical information, including follow-up data. All cases were reviewed to record pathologic features and to apply year 2000 and 2010 WHO classifications, as well as European Neuroendocrine Tumor Society and American Joint Committee on Cancer TNM stages. Clinical and pathologic characteristics were compared with disease outcome by contingency, univariate, and multivariate survival analyses. Although up to one third of cases presented several malignancy-associated pathologic features, only 4 patients died of the disease. Adverse outcome was significantly associated with extramural extension (including mesoappendix), well-differentiated carcinoma diagnosis (2000 WHO classification), pT3-4 stage, older age, and presence of positive resection margins, but not with tumor size, mitotic or proliferative indexes, and, consequently, 2010 WHO grading. In the appendix, at variance with midgut/hindgut NENs, the 2000 WHO classification performs better than the grading-based 2010 WHO scheme and, together with tumor stage, is the most relevant parameter associated with clinical aggressiveness.

A retrospective clinicopathological analysis of appendiceal tumors from 3,744 appendectomies: a single-institution study

PURPOSE

This study was conducted to describe the clinicopathological characteristics of appendiceal tumors and to evaluate their appropriate management.

METHODS

Between September 2000 and September 2005, 28 appendiceal tumors were identified by a retrospective review of 3,744 appendectomies.

RESULTS

Twenty-eight patients were found to have appendiceal tumors (incidence, 0.7%).The largest single group of tumors were benign mucinous cystadenomas (50%); carcinoids (32.1%) were next, and they were followed by malignant tumors (17.9%). Four out of five patients who had malignant appendiceal tumors presented with periappendiceal abscess. None of the patients was correctly diagnosed preoperatively. One-stage curative resection was possible in more than 76% of the patients, and the rate of making the correct preoperative diagnosis was 35%.

CONCLUSION

Most appendiceal tumors presented with appendicitis and periappendiceal abscess. Appendiceal tumors should be included in the differential diagnosis when an unexpected appendiceal mass is encountered during appendectomy.

Diagnosis and treatment of gastroenteropancreatic neuroendocrine tumors: current data on a prospectively collected, retrospectively analyzed clinical multicenter investigation

BACKGROUND

The aim of this prospectively collected, retrospectively analyzed clinical investigation was to describe "unmasked" clinical symptoms and methods of diagnosis, treatment, and short-term follow-up of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) diagnosed during 1 year in Austria.

METHODS

In total, 277 patients with GEP-NETs were documented. All tumors were immunhistochemically defined according to recently summarized criteria (World Health Organization, European Neuroendocrine Tumour Society). A standardized questionnaire comprising 50 clinical and biochemical parameters (clinical symptoms, mode of diagnosis, treatment, follow-up) was completed by attending physicians.

RESULTS

The most common initial symptoms were episodes of abdominal pain, diarrhea, weight loss, gastrointestinal bleeding, flushing, and bowel obstruction. Overall, 48.1% of tumors were diagnosed by endoscopy, 43.7% were diagnosed during surgery, 5% were diagnosed by fine-needle aspiration of the primary or metastases, and 2.5% were diagnosed during autopsy; 44.5% of tumors were not suspected clinically and were diagnosed incidentally during various surgical procedures. Overall, 18.7% of tumors were removed endoscopically and 67.6% were removed surgically; 13.7% of patients were followed without interventional treatment. Endoscopic or surgical intervention was curative in 81.4% of patients and palliative in 18.6% of patients. At the time of diagnosis, information on metastasis was available in 83.7% of patients with malignant NETs. Lymph node or distant metastases were documented in 74.7% of patients. In 19.3% of patients, 41 secondary tumors were documented, with 78.0% classified histologically as adenocarcinomas.

CONCLUSION

This investigation summarizes the clinical presentation and current practice of management of GEP-NETs and thereby extends the understanding and clinical experience.