Neuroendocrine tumors of the appendix

Visualizing the landscape of appendiceal tumor research after 2010: A bibliometric study

BACKGROUND

Despite the rarity of appendiceal tumors, research in this field has intensified, resulting in a growing number of studies and published papers. Surprisingly, no comprehensive bibliometric analysis has specifically addressed appendiceal tumors.

AIM

To offer a thorough analysis of the current landscape and future trends in appendiceal tumor research.

METHODS

In our bibliometric analysis studies, we explored the Web of Science Core Collection database. The bibliographic details of the chosen publications were automatically converted and analyzed using the bibliometric package in the R environment. Additionally, we employed VoSviewer to create cooperation network maps for countries, institutions, and authors, as well as clustering maps for keywords. Furthermore, CiteSpace, another software tool, was utilized to build dual-map overlays of journals and analyze references with citation bursts.

RESULTS

Our study included 780 English-language articles published after 2010. The number of related publications and citations has increased in the past decade. The United States leads in this area, but there is a need to improve cooperation and communication among countries and institutions. Co-occurrence analysis also revealed close collaboration among different authors. Annals of Surgical Oncology was the most influential journal in this field. Analysis of references with high co-citations and references with citation bursts, consistent with analysis of keywords and hotspots, indicated that current research primarily centers on the classification and management of appendiceal mucinous neoplasms and consequent pseudomyxoma peritonei. Despite the abundance of clinical studies, a greater number of in-depth basic research studies should be conducted.

CONCLUSION

Current research on appendiceal tumors focuses on classification and management of appendiceal mucinous neoplasms and pseudomyxoma peritonei. Enhanced collaboration and basic research are vital for further advancement.

Evaluation of immunohistochemical expression of novel neuroendocrine marker INSM1 and histological tumor growth pattern in well-differentiated neuroendocrine tumors of the appendix: 15-year single tertiary center experience

INTRODUCTION

Well-differentiated neuroendocrine tumors of the appendix (A-WDNET) are the most common neoplasms of the appendix but are rare and incidental. INSM1 is a novel transcription factor marker with high sensitivity and specificity for neuroendocrine differentiation. It may display architecturally diverse tumor growth patterns including solid, nest, insular trabecular, and acinar.

AIMS

The aim of this study was to determine the staining expression of INSM1 in A-WDNETs and detail the morphological tumor growth patterns.

MATERIALS AND METHODS

INSM1 immunohistochemistry was performed on 35 A-WDNET patients. Tumors were histologically classified according to their growth patterns.

RESULTS

Thirty-five patients, 60% of whom were male, had a mean age of 30 years at diagnosis and a mean tumor size of 0.9 cm. Eight percent of the tumors invaded the mucosa/submucosa, 34.3% showed invasion into the muscularis propria, 57.1% showed invasion into the subserosa or mesoappendix, LN metastasis was observed in two patients, lymph-vascular invasion in two patients, and perineural invasion in five patients. Ninety-four percent of the tumors were grade 1, the mitotic rate was >2% in two cases, and Ki-67 PI was >3% in two cases. INSM1 was positive in all cases (100%), 1+ 8.6%, 2+ 5.7%, 3+ 17.1%, 4+ 68.6%, weak staining in 11.4%, moderate staining in 22.9%, and strong staining in 67.7%. Type A histological growth pattern was observed in 54.3%, type B in 31.4%, and type C in 14.3% architecturally.

CONCLUSIONS

INSM1 was positive in all A-WDNET morphological patterns and was 100% sensitive. INSM1 IHC can be used as an alternative to traditional neuroendocrine markers or in combination with the diagnosis of neuroendocrine tumors.

An Update on Appendiceal Neuroendocrine Tumors

The mainstay of appendiceal neuroendocrine neoplasm (aNEN) treatment is surgery, based on simple appendectomy or right-sided hemicolectomy with lymphadenectomy (RHC). The majority of aNENs are adequately treated with appendectomy, but current guidelines have poor accuracy in terms of selecting patients requiring RHC, especially in aNENs 1-2 cm in size. Simple appendectomy is curative for appendiceal NETs (G1-G2) < 1 cm (if the resection status is R0), whereas RHC with lymph node dissection is recommended in tumors ≥ 2 cm in diameter, based on the high risk of nodal metastases in these cases. The clinical management of aNENs 1-2 cm in size is more controversial because lymph node or distant metastases are uncommon but possible. In our opinion, patients with tumor size > 15 mm or with grading G2 (according to WHO 2010) and/or lympho-vascular invasion should be referred for radicalization with RHC. However, decision-making in these cases should include discussion within a multidisciplinary tumor board at referral centers with the aim of offering each patient a tailored treatment, also considering that relatively young patients with long-life expectancy represent the majority of cases.

Appendiceal neoplasms: Suspected findings and reports of 14 cases

Background

Neoplastic lesions of the vermiform appendix are still considered to be rare, some studies suggest that appendix cancer may be on the rise, with an estimated incidence of 0.08-0.1% of all appendiceal specimens. The lifetime incidence of malignant appendiceal tumors ranges from 0.2 to 0.5%.

Patients and Methods

Our study is applied at the Department of General Surgery at tertiary training and research hospital; 14 patients who had appendectomy or right hemicolectomy between December 2015 and April 2020 were evaluated.

Results

The mean age of the patients was 52.3 ± 15.1 (range, 26-79) years. Gender of the patients were: five (35.7%) men and nine (64.3%) women. The clinical diagnosis was appendicitis without suspected findings in 11 (78.6%), appendicitis with suspected findings (appendiceal mass, etc.) in three (21.4%) of the patients, and there is no patient with asymptomatic or other rare findings. Surgeries applied for the patients were: nine (64.3%) underwent open appendectomy, four (28.6%) underwent laparoscopic appendectomy, and one (7.1%) underwent open right hemicolectomy. Histopathologic results were as follows: five (35.7%) neuroendocrine neoplasm, eight (57.1%), noninvasive mucinous neoplasm, and one (7.1%) adenocarcinoma.

Conclusion

While diagnosis and management of appendiceal pathology, surgeons should be familiar with suspected findings of appendiceal tumors and discuss them with patients to the possibility of histopathologic results.

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.

Epidemiology of neuroendocrine tumors of the appendix in the USA: a population-based national study (2014-2019)

Background

The appendix is the third most common place for neuroendocrine tumors (NETs) along the digestive tract and NETs are the most common neoplasms of the appendix. However, there are limited population-based data on the epidemiology of this disease. Using a large database, we sought to describe the epidemiology and risk association of NETs of the appendix.

Method

We queried a multi-institutional database (Explorys Inc., Cleveland, OH, USA), comprising 360 hospitals in the United States (US), for patients with a diagnosis of NETs of the appendix from 2014-2019.

Results

Of the 30,324,050 individuals in the database, 2020 patients had an appendiceal NET diagnosis (0.007%). The most common presenting symptoms included abdominal pain, nausea, vomiting and diarrhea. Patients with appendiceal NETs were more likely to be female (odds ratio [OR] 1.36, 95% confidence interval [CI] 1.24-1.49), Caucasian (OR 2.71, 95%CI 2.40-3.07), with a history of smoking (OR 1.82, 95%CI 1.65-2.01), family history of primary gastrointestinal malignancy (OR 7.26, 95%CI 6.31-8.33), diagnosis of multiple endocrine tumor type 1 (OR 52.31, 95%CI 23.15-118.23), or neurofibromatosis type 1 (OR 16.37, 95%CI 7.24-37.01).

Conclusions

In a population-based study in the US, using the Explorys database, we found the overall prevalence of NETs of the appendix to be 7 per 100,000 persons. The incidence in the year January 2019-January 2020 was 0.4 per 100,000 individuals. These rates are higher than previously reported and may be more accurate, given the more comprehensive nature of the Explorys database.

Diagnosis and Management of Gastrointestinal Neuroendocrine Neoplasms

The latest WHO classification cleanly divides gastrointestinal neuroendocrine neoplasms into neuroendocrine tumor (NET; well-differentiated, any grade) and neuroendocrine carcinoma (NEC; poorly differentiated, high-grade by definition), along with mixed neuroendocrine-non-neuroendocrine neoplasms. NECs are always aggressive, with multiple mutations; they are treated with chemotherapy. NETs have widely different presentations, behavior, and management depending on site of origin. Esophageal examples are vanishingly rare. Most gastric and appendiceal tumors are indolent, as are many colonic and rectal tumors. The duodenum is home to some unusual variants of NET, and jejunal/ileal NETs frequently metastasize, which impacts their staging and clinical management.

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.

Endometriosis and its relation with carcinoid tumor of the appendix: a systematic review

INTRODUCTION

The prevalence of appendiceal endometriosis ranges from 0.4% to 22%. The carcinoid tumor is the most common neoplasm of the appendix, with incidence ranging from 0.3% to 0.9%. Appendix lesions develop in up to 22% of women with deep infiltrative endometriosis. Even though these are most likely endometriosis, carcinoid tumors should always be considered. The aim of this review was to assess the prevalence of appendiceal carcinoid tumors and appendiceal endometriosis in patients undergoing gynecologic surgery, its association with endometriosis, and related symptoms.

EVIDENCE ACQUISITION

We included retrospective and prospective studies that assessed women who underwent appendicectomy in the past 20 years for appendiceal endometriosis and/or appendix carcinoid tumor confirmed by histological analysis. Results were reported as relative and absolute frequencies. Due to the heterogeneity of included studies, a statistical analysis (meta-analysis) was not performed.

EVIDENCE SYNTHESIS

The prevalence of appendiceal endometriosis was 15.2% in patients who underwent surgery for pelvic endometriosis and 11.4% in those who underwent benign gynecological surgery. Conversely, carcinoid tumors of the appendix were present in 2.4% of endometriosis patients and 1.3% of other benign gynecological surgeries.

CONCLUSIONS

The rates of carcinoid tumors in patients with endometriosis are the same as in the general population. Given the risk of a malignant appendiceal tumor, in all gynecological surgeries, especially those for endometriosis, the appendix should be inspected and removed if it has an abnormal appearance.

Neuroendocrine neoplasms of the appendix: Characterization of 335 patients referred to the Copenhagen NET Center of Excellence

INTRODUCTION

Neuroendocrine neoplasms (NEN) of the appendix are often incidentally discovered after appendectomy. Appropriate management is debated. The purpose was to characterize a cohort of 335 appendix NEN and evaluate the risk of recurrence.

METHODS

Retrospective collection of data from 335 patients referred to the Neuroendocrine Tumor Center at Rigshospitalet 2000-2019. Appendix goblet cell carcinoids and mixed neuroendocrine non-neuroendocrine neoplasms were excluded. Patients were followed until December 31st, 2019. No patients were lost to follow-up.

RESULTS

Sixty-three percent of the patients were female. The median (range) age at diagnosis was 34 (9-92) years. Median follow-up was 66 (1-250) months. Median tumor size was 7 (1-45) mm with 10 (3%) tumors >20 mm. In 18 specimens (5%) resection margins were positive. Mesoappendiceal invasion was found in 113 (35%). Sixty-three (19%) patients underwent right-sided completion hemicolectomy (RHC) after appendectomy according to ENETS guidelines. Among these, 11 (17%) had lymph node metastases in the resected tissue. Further, one patient who underwent initial RHC due to colonic adenocarcinoma had lymph node metastases. All lymph node metastases were detected in patients with serotonin positive tumors. No patients with glucagon positive tumors (n = 85) had lymph node metastases. Mesoappendiceal invasion >3 mm and positive resection margins were associated with presence of lymph node metastases. No recurrences were recorded.

CONCLUSION

Following ENETS guidelines may lead to overtreatment of patients with respect to completion RHC. The risk of over- and undertreatment needs to be further evaluated.

Neuroendocrine appendiceal tumor and endometriosis of the appendix: a case report

INTRODUCTION

Endometriosis of the appendix is very uncommon, accounting for only about 1% of all cases of endometriosis. However, endometriosis is found in the appendix in approximately 8-13% of patients with deep infiltrating endometriosis and is particularly common in patients with severe forms of deep infiltrating endometriosis. Neuroendocrine tumors are the most common neoplasms of the appendix and may be misdiagnosed when there are multiple endometriosis lesions in the pelvis.

CASE PRESENTATION

We describe a case of a Caucasian patient with deep infiltrating endometriosis with rectal involvement, retrocervical lesions, and a right ovarian endometrioma with no suspected lesions in the appendix. She underwent laparoscopy and, after a systematic intraoperative evaluation, suspected involvement of the appendix was observed. The patient underwent ovarian cystectomy, excision of the pelvic endometriosis lesions, appendectomy, and anterior stapler discoid resection. Histopathological analysis of the appendix revealed endometriosis and a well-differentiated neuroendocrine carcinoma at the appendix tip.

DISCUSSION

Our patient's case emphasizes the need to approach these lesions carefully and strengthens the indication for appendectomy when the appendix is affected in the setting of endometriosis. Despite the more likely diagnosis of appendiceal endometriosis, neuroendocrine tumors cannot be ruled out by imaging examinations, and both conditions can occur in the same patient.

Cytoreduction and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) Versus Surgery Without HIPEC for Goblet-Cell Carcinoids and Mixed Adenoneuroendocrine Carcinomas: Propensity Score-Matched Analysis of Centers in the Netherlands and Belgium

BACKGROUND

The value of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for patients with peritoneally metastasized goblet-cell carcinoids (GCCs) and mixed adenoneuroendocrine carcinomas (MANECs) is currently unclear. We compared outcomes of CRS-HIPEC to surgery alone for peritoneally metastasized GCCs and MANECs.

PATIENTS AND METHODS

Two cohorts were obtained from the Netherlands Cancer Registry (n = 569): patients with peritoneally metastasized GCCs and MANECs treated with CRS-HIPEC in Dutch and Belgian centers (n = 45), and patients treated with surgery alone. Primary outcome was overall survival (OS). Secondary outcomes were morbidity and hospital mortality. After propensity score matching, OS was compared in univariate and multivariate analyses. A systematic literature review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines from database inception to June 25, 2018.

RESULTS

After matching for sex, tumor stage, lymph node stage, and liver metastases, CRS-HIPEC was associated with improved median OS in the combined GCC and MANEC group and the separate GCC subgroup in univariate (GCC + MANEC: 39 vs. 12 months, P < .001; GCC: 39 vs. 12 months, P = .017) and multivariate analysis (GCC + MANEC: hazard ratio 4.27, 95% confidence interval 1.88-9.66, P = .001; GCC: hazard ratio 2.77, 95% confidence interval 1.06-7.26, P = .038). Acceptable grade III-IV morbidity (17.5%) and mortality (0) were seen after CRS-HIPEC. The literature review supported these findings.

CONCLUSION

CRS-HIPEC is associated with substantial survival benefit in patients with peritoneally metastasized GCCs and MANECs compared to surgery alone and is a safe treatment option. These data support centralized care of GCC and MANEC patients with peritoneal spread in expert centers offering CRS-HIPEC.

Novel Finding of Paired Box 5 (PAX5) Cytoplasmic Staining in Well-differentiated Rectal Neuroendocrine Tumors (Carcinoids) and Its Diagnostic and Potentially Prognostic Utility

Although nuclear immunostaining for paired box protein (PAX5) is widely used in practice, its cytoplasmic localization has not been evaluated. Recently we encountered cytoplasmic granular PAX5 staining in rectal well-differentiated neuroendocrine tumor (WD-NET) in the absence of nuclear staining. We investigated the specificity of this staining pattern for rectal NET (n=21) in comparison with 108 NETs, 1 WD rectal NET with elevated proliferation (WD-NET G3), and 40 poorly differentiated neuroendocrine carcinomas from the gastrointestinal and pancreatobiliary tract and liver. Representative tumor sections were subject to immunohistochemical stain for PAX5 antibody. Immunohistochemistry for 3 L-cell markers, glucagon-like peptide 1 and 2, and peptide YY, was performed on all rectal and appendiceal NETs and all other NETs with cytoplasmic PAX5 staining. Cytoplasmic PAX5 staining was observed in 90% (19/21) of rectal NET, 27% (3/11) of appendiceal, 14% (2/14) of pancreatic, 7% (2/29) of lung, 25% (3/12) metastatic NET in the liver, and 100% (1/1) of renal NET. No PAX5 cytoplasmic staining was seen in all grades of NET in other organs, rectal WD-NET G3, and all neuroendocrine carcinoma. L-cell marker staining was observed in all 21 (100%) rectal, in 3 of 3 (100%) PAX5-positive, and 1 of 7 (14%) PAX5-negative appendiceal NET. Cytoplasmic PAX5 staining is specific for rectal carcinoids. The sensitivity and specificity of PAX5 to detect L-cell type rectal carcinoids is 90% (19/21) and 100% (21/21), respectively. Cytoplasmic localization of the PAX5 protein may be utilized as a surrogate marker to detect L-cell type rectal carcinoids.

Appendiceal neuroendrocrine neoplasms: incidentaloma or something we should worry about?

PURPOSE OF REVIEW

To synthesize the current knowledge and guidelines on the management of appendiceal neuroendocrine neoplasms (ANENs).

RECENT FINDINGS

Most recent guidelines are essentially based on heterogeneous retrospective series. With the advent of a more precise classification of neuroendocrine neoplasms, this heterogeneity is rightly criticized and many 'grey areas' are now debated in expert literature. The only way to solve these issues is through the conduct of large prospective multicentre studies, but this seems somewhat utopian, given the rarity of this disease.

SUMMARY

ANENs are rare tumours with a favourable prognosis, and mainly diagnosed in young patients. They are predominantly localized, and diagnosed incidentally on appendectomy. This procedure is curative for the vast majority of patients but ANENs can relapse even a significant time after the first diagnosis. Identifying the risks for recurrence is challenging, with some factors thought to be predictive of nodal involvement. The presence of one or more of these factors justifies an oncological radicalization of the surgical procedure (right hemicolectomy with lymphadenectomy). However, the beneficial impact of this surgical procedure on survival is still unproven.

Appendiceal Nodules in the Setting of Endometriosis Can Be Carcinoid Tumors

Introduction:

Endometriosis is occasionally found in the appendix, particularly in severe forms of deep infiltrating disease. Carcinoid tumor is the most common neoplasm of the appendix and may be overlooked or misdiagnosed when there are multiple endometriosis lesions in the pelvis.

Case Description:

We describe two cases of carcinoid tumor diagnosed in patients who underwent surgery to treat endometriosis, in whom the diagnosis of appendiceal endometriosis was presumed.

Discussion:

In the context of endometriosis, surgery is indicated when the appendix is affected. Despite the more likely diagnosis of appendiceal endometriosis, carcinoid tumors cannot be ruled out by imaging examinations.

Goblet cell carcinoid tumor, mixed goblet cell carcinoid-adenocarcinoma, and adenocarcinoma of the appendix: comparison of clinicopathologic features and prognosis

CONTEXT

The prognosis of appendiceal goblet cell carcinoid tumors (GCTs) is believed to be intermediate between appendiceal adenocarcinomas and conventional carcinoid tumors. However, GCTs can have mixed morphologic patterns, with variable amount of adenocarcinoma.

OBJECTIVE

To evaluate the behavior of GCTs and related entities with variable components of adenocarcinoma.

DESIGN

We classified 74 cases of appendiceal tumors into 3 groups: group 1, GCTs or GCTs with less than 25% adenocarcinoma; group 2, GCTs with 25% to 50% adenocarcinoma; group 3, GCTs with more than 50% adenocarcinoma; and a comparison group of 68 adenocarcinomas without a GCT component (group 4). Well-differentiated mucinous adenocarcinomas were excluded. Clinicopathologic features and follow-up were obtained from computerized medical records and the US Social Security Death Index.

RESULTS

Of the 142 tumors studied, 23 tumors (16%) were classified as group 1; 27 (19%) as group 2; 24 (17%) as group 3; and 68 (48%) as group 4. Staging and survival differed significantly among these groups. Among 140 patients (99%) with available staging data, stages II, III, and IV were present in 87%, 4%, and 4% of patients in group 1 patients; 67%, 7%, and 22% of patients in group 2; 29%, 4%, and 67% of patients in group 3; and 19%, 6%, and 75% of patients in group 4, respectively (P = .01). Mean (SD) overall survival was 83.8 (34.6), 60.6 (30.3), 45.6 (39.7), and 33.6 (27.6) months for groups 1, 2, 3, and 4, respectively (P = .01). By multivariate analysis, only stage and tumor category were independent predictors of overall survival.

CONCLUSION

Our data highlight the importance of subclassifying the proportion of adenocarcinoma in appendiceal tumors with GCT morphology because that finding reflects disease stage and affects survival.

Histopathology of gastrointestinal neuroendocrine neoplasms

Gastrointestinal neuroendocrine neoplasms (GI-NENs) arise from neuroendocrine cells distributed mainly in the mucosa and submucosa of the gastrointestinal tract. In 2010, the World Health Organization (WHO) classification of NENs of the digestive system was changed, categorizing these tumors as grade 1 neuroendocrine tumor (NET), grade-2NET, neuroendocrine carcinoma (large- or small-cell type), or mixed adenoneuroendocrine carcinoma (MANEC). Such a classification is based on the Ki-67 index and mitotic count in histological material. For the accurate pathological diagnosis and grading of NENs, it is important to clearly recognize the characteristic histological features of GI-NENs and to understand the correct method of counting Ki-67 and mitoses. In this review, we focus on the histopathological features of GI-NENs, particularly regarding biopsy and cytological diagnoses, neuroendocrine markers, genetic and molecular features, and the evaluation of the Ki-67 index and mitotic count. In addition, we will address the histological features of GI-NEN in specific organs.

Management of gastrointestinal carcinoid tumours - 10 years experience at a district general hospital

BACKGROUND

There is paucity of guidelines regarding management of gastrointestinal carcinoid tumours in district hospitals.

METHODS

This study was undertaken at a district hospital to analyse the management pathway of gastrointestinal carcinoid tumours.

RESULTS

Over a period of 10 years there were 35 patients, with an estimated annual incidence of 2.5 per 100,000 population. After a median follow up of 24 months, 22 (63%) patients were alive and disease free. Only 56% patients were referred to the regional neuro-endocrine multidisciplinary team.

CONCLUSIONS

Management of patients with carcinoid tumours in district hospitals needs streamling with increased utilisation of regional neuroendocrine multidisciplinary teams.

[Surgical strategies for accidental detection of appendix carcinoids]

Carcinoids (neuroendocrine tumors NET) of the appendix are rare tumors and even today mostly detected only postoperatively by histopathology following operations for acute appendicitis or other abdominal procedures. Most NETs of the appendix are located at the tip of the appendix, less than 2 cm in size and non-metastasizing. Secondary right hemicolectomy with lymph node dissection bears a considerable risk of complications compared to simple appendectomy. To decide upon secondary surgery histopathological risk factors, such as grading, invasion of the mesoappendix, and tumor type in addition to tumor localization and size should be taken into consideration. Up to 20% of NETs of the appendix are associated with various neoplasms of the gastrointestinal tract. Follow-up examination should therefore also consider both appendix carcinoids and synchronous or metachronous neoplasms of the gastrointestinal tract.

Surgical cytoreduction and survival in appendiceal cancer peritoneal carcinomatosis: an evaluation of 46 consecutive patients

BACKGROUND

Surgical cytoreduction and intraperitoneal chemotherapy is increasingly accepted as an effective treatment modality for mucinous appendiceal neoplasm. For the majority of patients with low-grade histology, outcomes have been encouraging. The survival of patients with neoplasms of malignant character is protracted and this study was designed to evaluate the effectiveness of this surgical strategy on outcomes.

METHODS

Forty-six consecutive patients with mucinous and nonmucinous appendiceal cancer with peritoneal dissemination were studied. Clinicopathological and treatment related factors were obtained from a prospective database. The study's end points of disease-free survival (DFS) and overall survival (OS) were analyzed using the Kaplan-Meier method.

RESULTS

The median DFS and OS after cytoreduction were 20.5 and 56.4 months respectively. Five-year overall survival rate was 45%. Five independent factors associated with DFS and OS were identified through a multivariate analysis: age (DFS p = 0.001, OS p = 0.002), completeness of cytoreduction (DFS p = 0.001, OS p = 0.003), previous chemotherapy treatment (DFS p = 0.021), CA 199 levels (DFS p = 0.013), and tumor grade (OS p = 0.005).

CONCLUSIONS

Cytoreductive surgery and intraperitoneal chemotherapy may achieve long-term survival in appendiceal malignancies with peritoneal dissemination for which the predictors of outcomes identified through this study may tailor the disease management to commit patients early toward this successful surgical strategy.

[Appendiceal tumors found at appendectomy]

There are three main histologic types of appendiceal tumor: adenoma, adenocarcinoma, and neuroendocrine tumor. Neuroendocrine tumors (carcinoids) are by far the most common and account for two-third of all appendiceal tumors. Adenomas and adenocarcinomas are both rare; they share two particularities: (a) a mucinous component is both frequent and predominant, (b) they have a tendency to intraperitoneal dissemination. Rupture of any mucinous tumor-whether spontaneous or occurring during surgery-may result in pseudomyxoma peritonei; treatment of this condition requires complete resection of all lesions followed by hyperthermic intraperitoneal chemotherapy. For unruptured appendiceal tumor, the appendix should be removed by a carcinologic right hemicolectomy if the tumor appears aggressive.

Goblet or signet ring cells: that is the question

Goblet cell carcinoid tumor is a rare mixed endocrine-exocrine neoplasm of the appendix. It carries an intermediate biologic behavior between a classic carcinoid tumor and a conventional adenocarcinoma. There has been a general lack of clinicopathologic parameters that can be reliably used to predict the clinical course and patient outcome. A recent retrospective study of a large number of appendiceal goblet cell carcinoids has shown that these tumors can be stratified into 3 subgroups based on careful histologic analysis: typical goblet cell carcinoid (group A); adenocarcinoma ex goblet cell carcinoid, signet ring cell type (group B); and adenocarcinoma ex goblet cell carcinoid, poorly differentiated carcinoma type (group C). Clinical follow-up data show that the histologic classification correlates with patient survival. Thus, meticulous histologic evaluation is of critical importance in determining the prognosis and guiding the management of patients with goblet cell carcinoids. This brief review summarizes these recent findings and raises a few issues that may need to be further addressed to better apply this classification to our practice.

Appendectomy or right hemicolectomy in the treatment of appendiceal carcinoid tumors?

AIMS AND BACKGROUND

Carcinoids of the appendix continue to be of interest, despite their low incidence. There is still considerable controversy surrounding these tumors, especially with regard to the role of right hemicolectomy in the surgical management. The aim of this work was to explicate the current therapeutic knowledge and to review the criteria for the indications of appendectomy or hemicolectomy.

METHODS

The records of patients who underwent appendectomies from 1990 to 2000 were analyzed. Seven patients were included in the study. The clinical data were reviewed for demographic details, tumor size, localization in the appendix, histological patterns and surgical procedures. All patients underwent appendectomy including removal of the mesenteriolum, and in one of them a right hemicolectomy was performed 3 weeks later. The mean follow-up was 7 years (range, 4-14). Follow-up data included symptoms, urinary 5-hydroxyindoleacetic acid, ultrasound examination, computerized tomography, and octreotide scanning.

RESULTS

Seven patients (0.9% of all appendectomies) were reported to have carcinoid tumors of the appendix. They were 3 men and 4 women with a mean age of 29 years. All patients were admitted for appendicitis. None suffered from the carcinoid syndrome. The site of the tumor was the apex of the appendix in 4 cases, the body in 2 cases and the base in 1 case. Mean tumor diameter was 8 mm (range, 5-29 mm); in 6 patients it was <2 cm. Treatment was appendectomy in all cases; additional right hemicolectomy was necessary in one case because of a tumor of more than 2 cm with invasion of the mesoappendix and lymph nodes. The 7-year survival rate is 100%. Six patients are without disease, while 1 patient (the one who underwent a right hemicolectomy) developed metastases in the liver 6 years after the operation. This patient, who was treated with a liver resection, is still alive.

CONCLUSIONS

According to current guidelines, an appendectomy may be performed for small carcinoid tumors (<1 cm). Reasons for more extensive surgery than appendectomy are tumor size >2 cm, lymphatic invasion, lymph node involvement, spread to the mesoappendix, tumor-positive resection margins, and cellular pleomorphism with a high mitotic index. The criteria that direct us towards major (hemicolectomy) or minor surgery (appendectomy) are controversial. Tumor size is still considered the most important prognostic factor, with a presumed increase in the risk of metastasis for tumors greater than 2.0 cm. The accepted treatment of such tumors is a right hemicolectomy. However, there is no evidence demonstrating a survival benefit for right hemicolectomy over simple appendectomy in patients with carcinoids greater than 2.0 cm in diameter.

Ovarian Metastases of Appendiceal Tumors With Goblet Cell Carcinoidlike and Signet Ring Cell Patterns

Synchronous and metachronous ovarian and appendiceal mucinous tumors are often the subject of diagnostic consultations in gynecologic pathology practices to address whether the tumors are independent neoplasms or related as primary and metastasis. Those with goblet cell carcinoidlike patterns have not been extensively evaluated in a large series. Clinicopathologic features of 30 cases were examined. All patients presented with signs or symptoms related to a pelvic/adnexal or abdominal mass. The ovarian tumors were bilateral in 25 of 28 cases with data on both ovaries and were typically large (mean/median: 14 cm, range: 4.5 to 24.0 cm). The appendices were often firm or thickened but usually did not have a discrete measurable tumor and were not notably enlarged; microscopically, transmural invasion was present in all of them. The ovarian and appendiceal tumors exhibited a variety of patterns of differentiation, including signet ring cell and glandular, with all displaying some goblet cell carcinoidlike patterns (nests, islands, cords, or cryptlike tubules with goblet cells); teratomatous elements were not identified in any ovarian tumors. Chromogranin was expressed in 7 of 19 ovarian tumors (mean/median: 6.3%/0%; range: 0% to 20%) and synaptophysin was expressed in 4 of 18 of these (mean/median: 7.8%/0%; range: 0% to 90%). Chromogranin was expressed in 6 of 16 appendiceal tumors (mean/median: 11.9%/0%; range: 0% to 70%) and synaptophysin was expressed in 6 of 15 of these (mean/median: 16.7%/0%; range: 0% to 90%). Follow-up was available for 25 patients: 17 died of disease at intervals ranging from 4 to 47 months (mean/median: 18/16) and 8 were alive with disease at 1 to 25 months (mean/median: 11/10); median survival was 19 months and the 1-year and 2-year survival rates were 63% and 34%, respectively. The clinicopathologic features of these ovarian tumors indicate they should be labeled as metastatic appendiceal adenocarcinomas rather than as goblet cell carcinoid tumors both to reflect their behavior and help distinguish them from the rare true primary ovarian goblet cell carcinoid tumors. As the ovarian tumors have appreciable components of signet ring cells they qualify as Krukenberg tumors. In cases in which the primary tumor is not already evident, their "goblet cell carcinoidlike" patterns should direct attention to the appendix as a possible source.

Carcinoid tumor of the appendix: A consecutive series from 1237 appendectomies

AIM: To report the experience of the CHU Sart Tilman, University of Liège, Belgium, in the management of appendiceal carcinoid tumor.

METHODS: A retrospective review of 1237 appendectomies performed in one single centre from January 2000 to May 2004, was undertaken. Analysis of demographic data, clinical presentation, histopathology, operative reports and outcome was presented.

RESULTS: Among the 1237 appendectomies, 5 appendiceal carcinoid tumors were identified (0.4%) in 4 male and 1 female patients, with a mean age of 29.2 years (range: 6-82 years). Acute appendicitis was the clinical presentation for all patients. Four patients underwent open appendectomy and one a laparoscopic procedure. One patient was reoperated to complete the excision of mesoappendix. All tumors were located at the tip of the appendix with a mean diameter of 0.6 cm (range: 0.3-1.0 cm). No adjuvant therapy was performed. All patients were alive and disease-free during a mean follow-up of 33 mo.

CONCLUSION: Appendiceal carcinoid tumor most often presents as appendicitis. In most cases, it is found incidentally during appendectomies and its diagnosis is rarely suspected before histological examination. Appendiceal carcinoid tumor can be managed by simple appendectomy and resection of the mesoappendix, if its size is ≤ 1 cm.

Management of an unexpected appendiceal neoplasm

BACKGROUND

Appendiceal neoplasms are rare and most present unexpectedly as acute appendicitis. The classification and management are confusing, and there are few substantial reports in the literature.

METHODS

A systematic literature review was performed to access relevant publications on the presentation, pathology and management of appendiceal tumours.

RESULTS

Appendiceal tumours account for 0.4 to 1 per cent of all gastrointestinal tract malignancies and are found in 0.7 to 1.7 per cent of appendicectomy specimens. Carcinoid tumours are most common. Most are cured by simple appendicectomy if the tumour is less than 2 cm in size and does not involve the resection margin or mesoappendix. Epithelial tumours may present with, or in time develop, pseudomyxoma peritonei, the optimal management of which involves complete tumour resection and intraperitoneal chemotherapy, usually available only in specialized centres.

CONCLUSION

Suggested algorithms for the management of unexpected appendiceal tumours are provided. Recommendations are made for follow-up of patients with a perforated appendiceal epithelial tumour.

[Mixed endocrine tumors]

Mixed endocrine tumors are tumors composed of at least two distinct tumor populations, one of which is endocrine. Because of their rarity and unusual presentation, endocrine mixed tumors raise many problems of diagnosis, management and therapy. Three main types of endocrine mixed tumors are recognized: The existence of these various types has been confirmed by recent molecular studies, even if the same studies have also shown that the histogenesis of a mixed endocrine tumor cannot be predicted from its histological features. Composite tumors are the less rare mixed tumors. The recent WHO classification recommends to restrict the term of composite endocrine tumor to the epithelial tumors containing at least 30% of obviously tumoral endocrine cells; some authors recommend to use higher thresholds, of at least 50%, in order to avoid overdiagnosis. The endocrine component is usually well differentiated, easily identified by its suggestive histological features; the endocrine nature of tumor cells is confirmed by the immunodetection of specific endocrine and neuro-endocrine markers (such as chromogranin A and synaptophysin). In some cases, the endocrine component is poorly differentiated: the demonstration of neuro-endocrine markers is necessary to confirm the diagnosis. Mixed tumors can occur in every anatomical site; they are more frequent in organs containing endocrine cells in the normal state (especially the digestive tract and the pancreas), but they can also be observed in organs devoid of endocrine cells (such as the mammary gland). The management of mixed endocrine tumors must take into account the more aggressive component. Mixed tumors containing a well differentiated endocrine component and an adenocarcinomatous component are to be treated like adenocarcinomas. Mixed tumors containing a poorly differentiated endocrine component must be considered as poorly differentiated endocrine carcinomas.