Mucinous epithelial neoplasms of the appendix and pseudomyxoma peritonei

Mucocele of the rectal stump: mucinous cystic neoplasm with low-grade dysplasia simulating low-grade appendiceal mucinous neoplasm

Mucoceles, commonly observed in the appendix, are mucin-filled, dilated structures arising from a range of etiologies. Cases associated with dysplastic or neoplastic epithelium can rupture and disseminate within the abdominopelvic cavity. Similar lesions in other parts of the colon are exceedingly rare, with only 16 colonic mucoceles having been reported. The first case of a colonic mucinous neoplasm with dysplasia resembling a low-grade appendiceal mucinous neoplasm involving rectal stump was described in 2016. Here, we present the second such case arising in the rectal stump, identified in a 44-year-old male with extensive surgical history. Microscopic examination revealed low-grade dysplastic epithelium lining the cyst and mucin dissecting into the stroma, without evidence of rupture or extramural mucin. The patient was followed for 16 months without recurrence or peritoneal disease. The exact etiology and outcome of these rare lesions remain unknown, requiring close follow-up.

Low grade appendiceal mucinous neoplasm mimicking malignant ovarian tumor: A case report

INTRODUCTION

Mucinous appendiceal neoplasms are unique tumors in which >50 % of the tumor volume is composed of extracellular mucin. They may present as an unruptured mucin-filled appendix or, more commonly, with peritoneal metastases after rupture or transmural invasion of the primary tumor. This case report describes a case of presumed ovarian malignancy with final pathologic diagnosis of low grade appendiceal mucinous neoplasm. Due to its rarity, we decided to report it.

CASE PRESENTATION

A 37-year-old patient presented with a compliant of abdominal swelling. Abdominopelvic ultrasound was done and showed huge right and left complex cystic ovarian masses having thick septa. For this, she underwent total abdominal hysterectomy, omentectomy and bilateral salpingo-oophorectomy. On laparotomy there was also incidental finding of ruptured mucin-filled appendix for which appendectomy was done. Histopathology examinations from all resected specimens revealed the diagnosed LAMN. Two weeks after surgical resection, she was started on FOLFOX chemotherapy regimen.

DISCUSSION

Incidence of low grade appendiceal mucinous neoplasm is increasing. In addition to the increasing incidence, lack of early detection and impeded access to optimal multi-disciplinary treatment may worsen survival outcomes. Developing quality diagnostic services in the proper health context is crucial for early diagnosis and successful therapy of LAMN patients, and applying a resource-sensitive approach to prioritize essential treatments based on effectiveness and cost-effectiveness is key to overcoming barriers in low- and middle-income countries.

CONCLUSION

A recognition of mucinous material and abnormal appearing appendix should prompt the surgeon to consider performing an appendectomy to obtain primary pathologic diagnosis.

A Rare Case of Low-Grade Appendiceal Mucinous Neoplasm Presenting As Mucinous Vaginal Discharge

Appendiceal mucinous neoplasms (AMNs) are rare tumors that often present with non-specific symptoms, posing diagnostic challenges. This report aims to emphasize the importance of considering AMNs in the differential diagnosis of atypical pelvic symptoms, especially when initial evaluations suggest gynecological issues. A 56-year-old female with a past medical history of hyperlipidemia and a total vaginal hysterectomy performed over 20 years prior for abnormal uterine bleeding due to fibroids presented to her gynecologist with a three-week history of vaginal discharge and pelvic pain. Initial gynecological assessments were unremarkable, prompting a CT scan of the abdomen and pelvis, which revealed a markedly dilated, fluid-filled appendix, indicative of a mucinous neoplasm. The patient underwent laparoscopic right hemicolectomy, which confirmed a low-grade AMN with clear margins. Post-surgical follow-up showed no recurrence, and a surveillance colonoscopy one year later revealed a benign tubular adenoma. This case highlights the need to consider AMNs in the differential diagnosis of pelvic symptoms, particularly when initial gynecological evaluations do not identify a clear cause. AMNs can present with symptoms that overlap with those of gynecological conditions, making accurate diagnosis challenging. Effective management through early recognition and surgical intervention is important to prevent complications. This report demonstrates the value of comprehensive diagnostic evaluation and the importance of including rare tumors in the differential diagnosis of atypical pelvic symptoms.

Diagnostic uncertainty and management of low-grade appendiceal mucinous neoplasm-a case report and review of the literature

Low-grade appendiceal mucinous neoplasm (LAMN) is a rare entity identified in ~1% of patients undergoing appendectomy. The presentation often varies, making diagnosis challenging. Timely identification and treatment are critical to prevent rupture, which may lead to pseudomyxoma peritonei. We describe the case of a 41-year-old male who presented for evaluation of acute right lower quadrant abdominal pain. The clinical impression was consistent with appendicitis with a clinical suspicion for underlying malignancy. The patient was brought to the operating room for an exploratory laparotomy and right hemicolectomy, revealing low-grade appendiceal mucinous neoplasm. The diagnosis of low-grade appendiceal mucinous neoplasm can be challenging given the variable presentation and imaging findings. Early recognition and treatment are imperative to prevent progression to pseudomyxoma peritonei. Our case report seeks to contribute to the ongoing literature and provide a review of the current knowledge.

Diagnostic difficulties in the differentiation between an ovarian metastatic low‑grade appendiceal mucinous neoplasm and primary ovarian mucinous cancer: A case report and literature review

Low-grade appendiceal mucinous neoplasm (LAMN) is a tumor that primarily originates from the appendix and belongs to the family of appendiceal mucinous neoplasms (AMNs). In 50% of female patients, AMNs (particularly LAMNs) have a tendency to metastasize to organs in the genital tract, where the neoplasm can mimic the features of primary ovarian mucinous cancer (POMC). The present case report reviewed the difficulties in differentiating between these two types of tumors. In the present case report, a 61-year-old female patient was admitted to the Second Department of Gynecological Surgery and Gynecological Oncology, University Clinical Hospital no. 4 at Lublin Medical University (Lublin, Poland) with the diagnosis of a right ovarian mass. After performing ultrasound and computed tomography (CT) scans and laboratory analysis, the patient underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy, appendectomy and resection of the Douglas peritoneum. Notably, the postoperative pathological assessment revealed LAMN with metastases to the right ovary and omentum. Immunohistochemically, cytokeratin 20 and caudal type homeobox 2 both stained positively, whereas paired box gene 8 stained negatively. After surgery, the patient received the recommended hyperthermic intraperitoneal chemotherapy at the Department of Surgical Oncology at Lublin Medical University. After 1 year, a CT scan was performed, which indicated no evidence of recurrent disease. In conclusion, observations from the present case report suggest that gynecologists should be conscious of the possibility of malignancies of gastrointestinal origin in cases of ovarian tumors instead of making direct assumptions of POMC. If the mucinous mass involves the base of the appendix or if there is a suspicion of positive margins, then cytoreductive surgery and right-sided hemicolectomy must be performed. In addition, identifying the origin of mucinous tumors in the right ovary and/or the appendix requires the histopathological examination of a panel of markers using immunohistochemistry.

Mucocele of the appendix: our experience in treatment of rare pathologies

A mucocele of the appendix is a cystic formation of the appendix, the lumen of which is filled with mucin of varying consistency. There are benign and malignant forms of the disease. Its pathogenesis varies depending on the etiology and has not yet been fully studied. The clinical picture of this disease is nonspecific and there are difficulties in preoperative diagnosis. The purpose of the study is to present a rare clinical case of mucocele of the appendix, as well as literature data on this pathology. Successful treatment of a patient with appendix mucocele, an atypical location of the tumor was demonstrated. Based on the results of intraoperative express biopsy, as well as postoperative pathomorphological examination, surgical intervention was carried out to the required extent and with a favorable prognosis for the patient’s future life. Choosing the right method of surgical treatment allows you to avoid dangerous complications, such as the development of mucinous cystadenocarcinoma and pseudomyxoma peritonei. When performing surgery, it is necessary to be guided by the principles of safety from the patient’s point of view and not be afraid of performing access conversion.

Association between preoperative appendiceal histology grade and Pseudomyxoma peritonei grade offers a solution to avoid right hemicolectomy during cytoreductive surgery and HIPEC

INTRODUCTION & OBJECTIVES

Treatment of PMP consists of appendectomy, cytoreductive surgery (CRS) and HIPEC. Right-sided hemicolectomy is necessary only when PMP is high grade, given the lymphatic invasion risk. To date, no single preoperative factor was identified as predictive of PMP grade.

MATERIALS & METHODS

Preoperative factors of a prospective cohort study on PMP were retrospectively analyzed, in order to identify situations linked with high or low grade appendiceal PMP. The main outcome was PMP grade on definitive histology after CRS.

RESULTS

n = 105. In univariate analysis, the grade of the appendiceal tumor, systematically reviewed in an expert center, showed an OR of 25.00 (95 % CI: 3.30-189.27; p = 0.001) and an NPV of 93.75 [85.36, 100]. Peritoneal biopsy demonstrated an OR of 19.80 (95 % CI: 2.30-170.71; p = 0.002) and a PPV of 90 [71.41, 100]. In multivariate analysis, these two factors remained significantly associated with PMP grade.

CONCLUSION

Whenever appendiceal tumor is low grade on preoperative histology, the colon has to be spared unless completeness of CRS is compromised, which is a high-grade feature in fact. In case of high grade appendiceal tumor and/or peritoneal biopsy, right-sided hemicolectomy is warranted. If no histology is available preoperatively, adapt to intraoperative lesions as no preoperative factors seem to be predictive.

A Decade-Long Retrospective Clinicopathological Study of Appendiceal Neoplasms

INTRODUCTION

 Appendiceal neoplasms (ANs) are uncommon, representing less than 1% of all gastrointestinal tumors. They are most often discovered incidentally during appendectomies performed for suspected acute appendicitis. Recent studies have reported an increase in the incidence of AN. Our study aimed to analyze the spectrum of AN and determine the cases discovered incidentally.

MATERIAL AND METHODS

 This retrospective descriptive study was performed over 10 years, from March 2014 to March 2024, at Saveetha Medical College and Hospital in Chennai, India. Complete enumeration sampling was performed, and tumor registries were reviewed to identify all cases of AN received during the study period. The corresponding clinical and radiological data were obtained from the hospital database, whereas histopathology records were used to evaluate tumor characteristics. Descriptive statistical analysis was employed, and the spectrum of AN was analyzed.

RESULTS

 During the study period, 12 cases of AN were identified. Eleven cases (91.7%) were diagnosed from appendicectomy specimens, while one was from a right hemicolectomy specimen. Of these 12, nine cases (75%) were incidental findings. In our study, we found that there was a higher number of female cases, with nine out of twelve cases (75%) being female. Most patients presented with abdominal pain, and acute appendicitis was the most frequent preoperative diagnosis. Low-grade appendiceal mucinous neoplasm was the most common type encountered followed by other appendiceal tumors.

CONCLUSION

 The incidence of AN has increased in recent years, with most cases being found incidentally. Given the increasing rate of incidental AN, it is vital to maintain vigilance in specimen analysis including comprehensive examination and precise grossing to ensure malignancies are not overlooked.

Incidental Appendiceal Mucinous Neoplasm Found During Appendectomy in a 15-Year-Old Patient: A Case Report

Appendiceal mucinous neoplasms (AMNs) are rare gastrointestinal tumors, often underdiagnosed due to their variable presentation. Low-grade appendiceal mucinous neoplasms (LAMNs) are particularly significant because of their association with pseudomyxoma peritonei (PMP), a condition that increases the risk of abdominal recurrence. This report presents the case of a 15-year-old female with no prior medical history who developed nonspecific abdominal symptoms. Imaging revealed features consistent with appendicitis, leading to a laparoscopic appendectomy. Histopathological analysis confirmed a low-grade mucinous neoplasm confined to the appendix, with no perforation and clear surgical margins. The case underscores the importance of timely surgical intervention and accurate histopathological evaluation, as early diagnosis and appropriate management are crucial for preventing complications such as pseudomyxoma peritonei. This is particularly relevant in younger patients, where the early onset of such tumors is atypical. The rarity of appendiceal tumors and the need for precise surgical and pathological management are critical to improving patient outcomes and reducing the risk of recurrence.

Mucocele of the appendix: case report of a rare disease with changing diagnostic-therapeutic behavior

Mucinous appendicular neoplasms are a rare and heterogeneous group of tumors, whose treatment may vary based on histologic features and extent. We present a case of low-grade appendiceal mucinous neoplasm mimicking an acute appendicitis scenario. The patient underwent appendectomy along with resection of the caecal fundus. Choosing the correct treatment according to the case by following current guidelines is crucial to avoid under- or overtreatment.

Extra-appendiceal mucinous neoplasms: A tumour with clinicopathologic similarities to low- and high-grade appendiceal counterpart

AIMS

Appendiceal mucinous neoplasms feature neoplastic mucinous epithelium with pushing borders and densely fibrotic walls. We have identified five examples of analogous colorectal tumours.

METHODS AND RESULTS

Slides, pathology reports, and clinical data were reviewed. Whole genome sequencing was performed in two cases. Three were women and the mean age was 70. Associated GI conditions included Crohn's disease [1], diverticulosis [2], and sarcoma of the terminal ileum [1]. Signs/symptoms included obstruction [2], nausea, vomiting, abdominal pain [1], and positive faecal immunohistochemical test [1]. Colonoscopic findings included narrowing [1], "fullness" [1], and caecal lesion concerning for GIST [1]. Tumours involved the rectosigmoid [2], sigmoid [1], transverse colon [1], and cecum [1] and ranged from 1.5 cm to 8.5 cm. All but one tumour arose in the setting of faecal stream abnormalities related to obstruction, diverticulosis, or bowel diversion. All cases showed columnar, variably mucinous epithelium associated with little-to-no lamina propria. All but one case showed fibrosis of the submucosa. Three cases had high-grade areas. Neoplastic glands and/or mucin dissected through the muscularis propria or subserosa in 3 examples. No extracolonic neoplastic cells/mucin, infiltrative invasion, or desmoplastic response were identified. Three patients with available follow-up [5.5-28 months] are alive. Whole genome sequencing identified pathogenic TP53 and ERBB2 variants, as well as ERBB2 copy number amplification in one high-grade example.

CONCLUSIONS

Though these tumours share clinicopathologic characteristics with their appendiceal counterparts, our cohort is too small to draw solid conclusions. We propose the term "extra-appendiceal mucinous neoplasm [EAMN]" for these rare lesions.

An Incidental Finding of Low-Grade Appendiceal Mucinous Neoplasm in a Case of Borderline Brenner Tumor of the Ovary

The concurrent presentation of a low-grade appendiceal mucinous neoplasm (LAMN) and a borderline Brenner tumor (BT) of the ovary are exceedingly rare. Brenner tumors stand out as a particularly uncommon form, making up only around 5% of all benign epithelial tumors of the ovary. Among the ovarian Brenner, the borderline subtype is even rarer. Appendiceal neoplasm (LAMN) and right ovarian BT cannot be distinguished due to their anatomical position. LAMN is often an incidental finding and at later stages when left undiagnosed may lead to pseudomyxoma peritonei (PMP). This case describes a postmenopausal woman in her 50s experiencing abdominal pain and bloating for a week. Elevated carcinoembryonic antigen (CEA) levels and imaging suggested a potential right ovarian tumor. Interestingly, it revealed a unique combination of borderline Brenner tumor of the right ovary and low-grade appendiceal mucinous neoplasm.

Low-grade appendiceal mucinous neoplasms: Histomorphological spectrum in a tertiary care hospital

BACKGROUND

Low-grade appendiceal mucinous neoplasms (LAMNs) are benign non-invasive epithelial proliferations of the appendix. These usually present clinically as mucoceles and these rarely exceed 2 cm in diameter. Lesions confined to the lumen are labelled as LAMN; however those in which mucin spreads outside the peritoneum are labeled as pseudomyxoma peritonei (PMP).

AIMS AND OBJECTIVE

A retrospective study was conducted over a period of three years and all cases of appendectomies were studied. Twelve cases of LAMN were identified, which is a diagnostic dilemma for the pathologists and clinicians.

RESULTS

LAMN was identified based on the histopathological features. Out of the 12 cases, 9 were classified as LAMN and 3 as appendiceal neoplasm with PMP. There was villous or flat proliferation of epithelial lining, loss lymphoid aggregates, and dissecting mucin within muscularis.

CONCLUSION

LAMNs are rare neoplasms of the appendix, with clinical presentation similar to acute appendicitis. Mucinous collections within the appendiceal wall should be extensively searched for mucosal changes and, if found, should prompt a careful search for pushing invasion of LAMNs. A thorough and vigilant gross examination can be of great help. Appendicectomy is the treatment of benign and grossly intact mucinous neoplasm.

Active surveillance for low-grade appendiceal mucinous neoplasm (LAMN)

Objectives

Due to the scarcity of low-grade appendiceal mucinous neoplasm (LAMN), there is an absence of systematized guidelines concerning its management, especially after incidental finding on an appendiceal specimen. In this study, we evaluate the active surveillance (AS) strategy adopted for a series of patients diagnosed with LAMN on resection specimens who were considered to have a low risk of pseudomyxoma progression.

Methods

Thirty patients were included between April 2014 and July 2021, with a female majority and a median follow-up period of 3.1 years. The inclusion criteria were as follows: LAMN diagnosis on appendiceal specimens, confirmed in an expert center, limited extra-appendiceal mucin resected and localized around the appendix, normal biology (CEA, CA199, CA125) and normal abdominopelvic MRI. AS included physical exam (trocar scar), biology and MRI, 6 months postoperatively, then yearly for 10 years.

Results

As an initial surgery, 77 % had an appendectomy as their initial intervention, 17 % had a cecectomy, and 6 % had a right colectomy. After follow-up, 87 % of patients showed no sign of disease progression by MRI, while 13 % progressed to PMP. MRI performed in the first postoperative year predicted the disease prognosis in 97 % of patients.

Conclusions

The AS strategy, based on MRI, is a valid option after incidental LAMN diagnosis.

The value of ultrasound combined with CT in identifying early low-grade appendiceal mucinous neoplasm and appendicitis

Objective

The aim of this study is to investigate the value of ultrasound combined with computed tomography (CT) in identifying early low-grade appendiceal mucinous neoplasm and appendicitis.

Methods

Patients with early low-grade appendiceal mucinous neoplasm and appendicitis from September 2017 to September 2021, including 40 patients with low-grade appendiceal mucinous neoplasm and 40 patients with appendicitis, were collected in this study. Clinical data as well as ultrasound and CT findings of all patients were retrospectively analyzed. Univariate and multivariate logistic regression analyses were applied to establish the ultrasound model, the CT model, and the combined model.

Results

The nomogram showed that specific characteristics of CT were dilated appendiceal diameter and clear surrounding fat space in the low-grade appendiceal mucinous neoplasm and that specific characteristics of ultrasound were thin or clear layer appendix wall and flocculent echo in the appendix cavity. These four features were used to construct a nomogram for predicting early low-grade appendiceal mucinous neoplasm, and the area under the curve value was 0.839.

Conclusion

Ultrasound combined with CT for diagnosis of early low-grade appendiceal mucinous neoplasm has a significant value; when found significantly dilated appendix in the lower right abdomen, with thin wall, wall calcification, clear surrounding fat space, and progressive enhancement, especially non-specific symptoms similar to appendicitis, the physician should timely consider the possibility of low-grade appendiceal mucinous neoplasm.

Low-Grade Appendiceal Mucinous Neoplasm: What Is the Best Treatment?

BACKGROUND

Low-grade appendiceal mucinous neoplasm (LAMN) is an uncommon tumor of the appendix that is usually diagnosed incidentally after surgery. Although LAMN may be asymptomatic, it can rupture and seed mucin and neoplastic epithelium into the peritoneum, causing pseudomyxoma peritonei (PMP).

MATERIALS AND METHODS

Data from 53 patients were retrospectively analyzed. Age, sex, tumor size, margin status, peritoneal carcinomatosis index, surgical procedures, postoperative results with histologic diagnosis, T stage, recurrence, and mortality of the patients were evaluated.

RESULTS

Appendectomy was performed in 37 patients, right hemicolectomy in nine patients, cytoreductive surgery in one patient, and cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in six patients. Recurrence occurred in four patients. Of the patients who developed recurrence, one patient had stage T4a disease, and the other three patients had T4b disease (p<0.001). Eighteen patients had acellular mucin in the serosa and four of these patients developed recurrence (p=0.004). Twelve patients had appendix perforation, and three of these patients had PMP on exploration (p<0.001). The mean survival time was 93.3 months in patients without recurrence and 32 months in patients with recurrence (p=0.021).

CONCLUSIONS

Low-grade appendiceal mucinous neoplasms are rare appendiceal tumors. The appropriate management of this tumor is controversial. T stage, appendix perforation, presence of acellular mucin on the serosa, and surgical margins are risk factors for the development of PMP. Appendectomy is considered sufficient when there are no risk factors for Tis (LAMN) and T3 disease. Right hemicolectomy may be sufficient if there are no risk factors for T4a disease, but cytoreductive surgery and hyperthermic intraperitoneal chemotherapy seem to be the most appropriate treatments in the presence of the stated risk factors for T4b disease.

Low grade appendiceal mucinous neoplasm metastatic to the ovary: A case report and intraoperative assessment guide

INTRODUCTION

Incidence of low grade appendiceal mucinous neoplasm is increasing. Preoperatively, it may present similarly to primary ovarian malignancy. This case report describes a case of presumed ovarian malignancy with final pathologic diagnosis of low grade appendiceal mucinous neoplasm. We also propose several surgical strategies to approach this conundrum.

PRESENTATION OF CASE

A postmenopausal woman with abdominal pain was found to have a 30 cm abdominopelvic mass with elevated CA-125 and CEA presumably a primary ovarian malignancy. During surgical staging, intraoperative findings were notable for an appendiceal mass. Intraoperative surgical oncology consultation recommended appendectomy for diagnostic purposes. Following primary surgery and final pathologic diagnosis, she underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

DISCUSSION

Low grade appendiceal mucinous neoplasm should be within the differential diagnosis of gynecologic surgeons when presented with a patient with large volume ascites and biopsy of acellular mucin. Intraoperatively, an abnormal appearing appendix with normal appearing gynecologic structures should trigger suspicion for appendiceal rather than ovarian origin. Preoperative symptoms, imaging studies, tumor markers, and frozen section pathology may not be able to differentiate between appendiceal and epithelial ovarian malignancies.

CONCLUSION

A recognition of mucinous material and abnormal appearing appendix should prompt the surgeon to consider performing an appendectomy to obtain primary pathologic diagnosis. A high level of suspicion could better optimize the patient for a joint case with the appropriate surgeons. Given the documented disguise of low grade appendiceal mucinous neoplasm as primary ovarian cancer and its increasing incidence, diagnosis and general understanding of treatment should be understood.

Durable Response after Repeat Cytoreductive Surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) in a Patient with Extensive Mucinous Adenocarcinoma of the Appendix

Mucinous adenocarcinoma of the appendix is a rare form of lower gastrointestinal (GI) tract cancer. These cancers have a high tendency to progress towards peritoneal metastasis and their response to systemic treatment is typically low. Together, cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) have become an established form of therapy used to prolong the survival of patients with this disease. Repeat CRS and HIPEC have been shown to be feasible in selected patients with GI peritoneal carcinomatosis (PC), among which those with appendix cancer receive the greatest benefit. The peritoneal cancer index (PCI) and completeness of cytoreduction have been shown to be important predictors of outcomes. However, repeat cytoreduction in patients with a high-volume peritoneal tumor burden (peritoneal cancer index (PCI) > 30) is not typically performed due to concerns regarding morbidity and mortality. Herein, we describe a case of repeat CRS and HIPEC for extensive appendiceal mucinous peritoneal carcinomatosis after initial incomplete cytoreduction and durable remission of 28 months without adjuvant chemotherapy. In appendiceal mucinous cancers, repeat CRS can achieve a durable response despite an initial failed CRS and high-volume disease.

Preoperative prediction of malignancy and surgical treatment strategy in appendiceal tumors: multicenter review of 51 consecutive cases

PURPOSE

A diagnostic and treatment strategy for appendiceal tumors (ATs) has not been established. We aimed to evaluate our treatment strategy in ATs, including laparoscopic surgery (LS), and to identify preoperative malignancy predictors.

METHODS

A total of 51 patients between 2011 and 2021 were retrospectively reviewed. Data, including tumor markers and imaging findings, were compared between carcinoma and non-carcinoma patients. Validity of planned operation was evaluated based on pathological diagnosis.

RESULTS

Twenty-five patients were diagnosed with carcinoma, 13 with low-grade mucinous neoplasm, and 13 with other diseases. Symptoms were more commonly present in carcinoma patients than in non-carcinoma patients (68.0% vs. 23.1%, p = 0.001). Elevated CEA and CA19-9 were more frequently observed in carcinoma patients than in non-carcinoma patients (p < 0.01 and p = 0.04, respectively). Five carcinoma patients had malignancy on biopsy, compared with zero non-carcinoma patients. Significant differences were noted in the percentages of carcinoma and non-carcinoma patients with solid enhanced mass (41.7% vs. 0%, p < 0.001) and tumor wall irregularity (16.7% vs. 0%, p = 0.03) on imaging. Although the sensitivity was not high, the specificity and positive predictive value of these findings were 100%. Forty-two patients (82.4%) underwent LS as minimally invasive exploratory and/or radical operation, of whom 2 were converted to open surgery for invasion of adjacent organ. No patients had intraoperative complications or postoperative mortality.

CONCLUSION

Clinical symptoms, elevated tumor markers, and worrisome features of solid enhanced mass and tumor wall irregularity on imaging can be malignancy predictors. For management of ATs, LS is feasible and useful for diagnosis and treatment.

Clinicopathologic parameters and outcomes of mucinous neoplasms confined to the appendix: a benign entity with excellent prognosis

Appendiceal mucinous neoplasms (AMNs), characterized by expansile or "pushing" growth of neoplastic epithelium through the appendix wall, are sometimes accompanied by peritoneal involvement, the extent and grade of which largely determine clinical presentation and long-term outcomes. However, the prognosis of tumors entirely confined to the appendix is still debated and confusion remains regarding their biologic behavior and, consequently, their clinical management and even diagnostic nomenclature. We evaluated AMNs limited to the appendix from 337 patients (median age: 58 years, interquartile range (IQR): 47-67), 194 (57.6%) of whom were women and 143 (42.4%) men. The most common clinical indication for surgery was mass or mucocele, in 163 (48.4%) cases. Most cases (N = 322, 95.5%) comprised low-grade epithelium, but there were also 15 (4.5%) cases with high-grade dysplasia. Lymph nodes had been harvested in 102 (30.3%) cases with a median 6.5 lymph nodes (IQR: 2-14) per specimen for a total of 910 lymph nodes examined, all of which were negative for metastatic disease. Histologic slide review in 279 cases revealed 77 (27.6%) tumors extending to the mucosa, 101 (36.2%) to submucosa, 33 (11.8%) to muscularis propria, and 68 (24.4%) to subserosal tissues. In multivariate analysis, deeper tumor extension was associated with older age (p = 0.032; odds ratio (OR): 1.02, 95% confidence intervals (CI): 1.00-1.03), indication of mass/mucocele (p < 0.001; OR: 2.09, CI: 1.41-3.11), and wider appendiceal diameter, grossly (p < 0.001; OR: 1.61, CI: 1.28-2.02). Importantly, among 194 cases with at least 6 months of follow-up (median: 56.1 months, IQR: 24.4-98.5), including 9 high-grade, there was no disease recurrence/progression, peritoneal involvement (pseudomyxoma peritonei), or disease-specific mortality. These data reinforce the conclusion that AMNs confined to the appendix are characterized by benign biologic behavior and excellent clinical prognosis and accordingly suggest that revisions to their nomenclature and staging would be appropriate, including reverting to the diagnostic term mucinous adenoma in order to accurately describe a subset of them.

An Ex Vivo Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

PURPOSE

Epithelial neoplasms of the appendix are difficult to study preclinically given their low incidence, frequent mucinous histology, and absence of a comparable organ in mice for disease modeling. Although surgery is an effective treatment for localized disease, metastatic disease has a poor prognosis as existing therapeutics borrowed from colorectal cancer have limited efficacy. Recent studies reveal that appendiceal cancer has a genomic landscape distinct from colorectal cancer and thus preclinical models to study this disease are a significant unmet need.

EXPERIMENTAL DESIGN

We adopted an ex vivo slice model that permits the study of cellular interactions within the tumor microenvironment. Mucinous carcinomatosis peritonei specimens obtained at surgical resection were cutoff using a vibratome to make 150-μm slices cultured in media.

RESULTS

Slice cultures were viable and maintained their cellular composition regarding the proportion of epithelial, immune cells, and fibroblasts over 7 days. Within donor specimens, we identified a prominent and diverse immune landscape and calcium imaging confirmed that immune cells were functional for 7 days. Given the diverse immune landscape, we treated slices with TAK981, an inhibitor of SUMOylation with known immunomodulatory functions, in early-phase clinical trials. In 5 of 6 donor samples, TAK981-treated slices cultures had reduced viability, and regulatory T cells (Treg). These data were consistent with TAK981 activity in purified Tregs using an in vitro murine model.

CONCLUSIONS

This study demonstrates an approach to study appendiceal cancer therapeutics and pathobiology in a preclinical setting. These methods may be broadly applicable to the study of other malignancies.

Low-Grade Appendiceal Mucinous Neoplasm: A Case Series

Low-grade appendiceal mucinous neoplasm (LAMN) is a lesion of the appendix with potentially fatal consequences if untreated. Though LAMN can be asymptomatic and stable, it can rupture and seed mucin and neoplastic epithelium into the peritoneum, leading to pseudomyxoma peritonei (PMP), a serious complication characterized by intraperitoneal accumulation of mucinous tumors and ascites with a high morbidity and mortality rate. Therefore, timely identification and treatment of LAMN are crucial for reducing PMP risk and improving prognosis and outcome. This case series sought to examine five LAMN cases and delineate the strategies for managing LAMN and progression to rupture and PMP.

Appendiceal Endometriosis with Intestinal Metaplasia Mimicking Appendiceal Mucinous Neoplasm - A Case Report and a Concise Review for the Practicing Pathologist

Appendiceal endometriosis is a rare entity and, when accompanied by intestinal metaplasia, represents a challenging differential diagnosis with low-grade appendiceal mucinous neoplasm (LAMN). We present the case of a 47 years-old woman, with multiple surgical interventions for endometriosis, with persistent symptoms despite chronic hormonal treatment, with imaging showing stage IV endometriosis. Hence, en bloc low rectum resection with total hysterectomy and bilateral adnexectomy was performed, followed by appendectomy. Unexpectedly, despite the gross normal macroscopic appearance of the appendix, microscopy showed multiple endometriosis foci, consisting of endometrial glands embedded in varying amounts of endometrial stroma. As some of these glands were bordered by mucinous-type epithelium containing intestinal cells, Goblet cells, Paneth cells in addition to the presence of mucus-filled microcysts, immunohistochemistry (IHC) was performed in order to differentiate between intestinal-metaplasia and LAMN. IHC showed positivity of the endometrial epithelium for KRT7, estrogen receptor (ER) and progesterone receptor (PR). Both the appendiceal mucosa and the intestinal-type metaplastic epithelium of the glandular structures were positive for KRT20. Additionally, the endometrial stroma enclosing endometrial glands, as well as the stroma surrounding mucinous-type metaplastic epithelium, were positive for CD10, ER and PR. This patient's case draws attention to the rare occurrence of appendiceal endometriosis and the uncommon intestinal metaplasia, which can easily mimic LAMN, emphasizing the paramount importance of the differential diagnosis with this type of neoplasia.

Appendiceal mucocele presenting as a leading point in ileocolic intussusceptions: "Case report"

INTRODUCTION AND IMPORTANCE

Appendiceal mucocele is a rare clinical scenario, which is found in 0.2-0.7 % of appendectomies. Ileocecal/ileocolic intusception caused by appendiceal mucocele is an extremely rare condition with few case reports in literatures. The treatment is surgery with the extent determined by intra-operative findings. Ultrasound and CECT scan can suggest the diagnosis, but definitive diagnosis is by histopathology. The aim of this presentation is to discuss appendiceal mucocele in terms of clinical features, diagnostic imaging and treatment. This case report can create awareness to primary care physicians, radiologists, surgeons and pathologists aiding in accurate diagnosis and early surgical intervention to prevent rupture.

PRESENTATION OF THE CASE

A fifty years old woman presented with intermittent colicky peri umbilical abdominal pain of one-week duration. She had nausea, vomiting, mild abdominal distension, and failure to pass feces and flatus. Physical examination was normal. Imaging suggested ileocolic intussusceptions with cystic leading point on ultrasound, but on CECT scan, no leading point reported. Appendiceal mucocele diagnosed intra operatively and confirmed by pathology.

CONCLUSION

Appendiceal mucocele is rare and can be benign or malignant. Preoperative diagnosis is often difficult. Definitive diagnosis is by histopathology. Appendiceal mucocele can rarely present with ileocolic intussusceptions. Radiologists, pathologists, primary care physicians and surgeons must be aware of this condition. Accurate preoperative diagnosis and early surgical treatment of appendiceal mucocele is important to prevent complications like pseudo myxoma peritonei(PMP), which has poor prognosis.

A proposal for changing nomenclature from pseudomyxoma peritonei (PMP) to abdomino-peritoneal mucinous carcinoma (APM) based on its long journey and experience from tertiary oncology center in India

Introduction

Pseudomyxoma peritonei (PMP) is a generalized term, usually known as “jelly belly” since 1884. Incidence is very low, 1–3 per million people per year. Because of its indolent nature, it is usually diagnosed at an advanced stage, thereby impacting the quality of life. The 5-year survival rate varies from 23 to 86% in world literature. Even 10 years and 20 years of survival have been described. With our experience, we like to propose rename of PMP as abdomino-peritoneal mucinous carcinoma (APM) as we strongly feel the time has come to specify the term and standardize the management strategy.

Methodology

In the premier institute of India and as a tertiary referral center, we experienced the maximum number of advanced cases of APM. From 2012 to 2021, we analyzed all the APM patients based on a prospectively maintained computerized database in the department of surgical oncology and found the reasons for renaming from this traditional one.

Results

We included a total of 87 patients who underwent surgical intervention. Thirty-five patients underwent cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC), and 52 patients underwent debulking. In CRS-HIPEC patients, CC-0 was achieved in 28 patients (80%), CC-1 in 4 patients (11.4%), and CC-2 in 3 patients (8.6%). Palliative intent HIPEC was done in 3 patients (8.6%). Clavien-Dindo grade III and IV morbidity was observed in 18.8% of patients with 90 days mortality of 5.7%.

Conclusion

With our long-term experience and advancement of scientific evidence, we like to propose a new name for PMP as APM. We strongly believe this paper will give a clear picture of this rare disease and standard management outlines.

Comprehensive Understanding and Evolutional Therapeutic Schemes for Pseudomyxoma Peritonei: A Literature Review

Pseudomyxoma peritonei is an infrequent solid tumor in clinical practice. The low morbidity and deficient understanding of this mucus-secreting malignant disease increase the risks of delayed identification or uncontrollable deterioration. In quite a lot cases, patients go through complete cytoreduction surgery and hyperthermic intraperitoneal chemotherapy could receive a long time survival over 5 years. But the recurrence rate is also hard to overlook. Unlike other types of cancer, the standard treatment for this considerable groups has not been confirmed yet. With the advanced medical progression, studies have been carrying out based on pathogenesis, biological characters, and mutated gene location. All but a few get statistical survival benefits, let alone the breaking progress on research or therapeutic practice in the field. We try to give a comprehensive exposition of pseudomyxoma peritonei around the epidemiology, radiologic features, clinical manifestation, present treatment and promising schemes, hoping to arise much attention and reflection on the feasible solutions, especially for the recrudescent part.

Validating the PSOGI classification of peritoneal disease from non-carcinoid epithelial appendiceal neoplasms in the curative and palliative setting: an observational retrospective study

BACKGROUND

Few studies on long-term survival have been published since the new updated pseudomyxoma peritonei (PMP) classification was published in 2016. The aim was to investigate long-term survival according to the Peritoneal Surface Oncology Group International (PSOGI) classification and compare prognostic factors.

METHODS

From Uppsala University Hospital, consecutive patients referred for cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) from 2004 to 2017 with peritoneal disease from non-carcinoid mucinous epithelial appendiceal neoplasms were included in the study. The peritoneal disease was divided into four groups: mucin only, low-grade mucinous carcinoma peritonei (MCP-1), high-grade (MCP-2), and high-grade with signet ring cells (MCP-3). Survival curves were rendered, and prognostic factors were compared.

RESULTS

The study included 223 patients: 36 with mucin only, 112 with MCP-1, 70 with MCP-2, and 5 with MCP-3. Thirty-eight patients had a palliative debulking or open/close procedure. The 5- and 10-year overall survival was 97% and 97% for mucin only, 83% and 70% for MCP-1, 69% and 49% for MCP-2, with no patients still under follow-up after 5 years in the MCP-3 group. In a multivariable analysis, completeness of cytoreduction (CC) score 2-3 and PSOGI class MCP-3 were significantly associated with lower survival. The 5-year overall survival in the palliative setting was 40% vs. 44% (MCP-1 vs. MCP-2, P>0.05) with median survival 51 vs. 53 months, respectively.

CONCLUSIONS

The PSOGI classification of PMP provides a solid differentiation of prognostic groups after CRS/HIPEC treatment, but not in the palliative setting.

LAMN as a differential diagnosis for abdominal pain: a case report from Syria

Low-grade appendiceal mucinous neoplasms (LAMNs) are papillary or flat mucinous tumors with low-grade cytologic atypia found in &lt;0.3% of appendectomy specimens among older population. They are the most frequent source of pseudomyxoma peritonei. They can be easily misdiagnosed, due to unspecific symptoms, with acute appendicitis, retroperitoneal tumors or adnexal mass. Macroscopically, the appendix may appear normal or be variably dilated. Microscopic study determines whether the studied specimen is LAMN or mucinous adenocarcinomas. We report a 77-year-old patient presented with 15-day abdominal pain accompanied with chills and hyperthermia. Decision was made for right hemicolectomy as a result of the findings on ultrasound and computed tomography scan. Diagnosis was made after the pathologic study, which revealedLAMN.

Appendiceal tumours - A correlation of CT features and histopathological diagnosis

Appendiceal tumours are uncommon neoplasms of the gastrointestinal tract. An understanding of the imaging appearances facilitates an accurate radiological description, which guides surgical and oncological management. In this study, a retrospective review of the CT imaging and histopathology of all cases of appendiceal tumours discussed at the oncology multidisciplinary meetings in a single centre, over an 8-year period (2012-2019) is performed. The array and incidence of both common and rare pathologies are investigated, and important characteristic imaging findings for radiologists to recognize are highlighted.

Enterocutaneous fistula resulting from the drainage of a contained appendiceal perforation secondary to a partially obstructing low-grade appendiceal mucinous neoplasm

We report a case of an enterocutaneous fistula resulting from drainage of a contained appendiceal perforation secondary to an obstructing appendiceal mucinous neoplasm. A 66-year-old otherwise healthy female patient proceeded to laparoscopic appendicectomy with resection of the fistula tract. Histopathology demonstrated a mid-appendiceal mucinous neoplasm, with a benign enterocutaneous fistula tract communicating with the distal, non-malignant portion of the appendix. We provide an overview of the literature and highlight the need to consider appendiceal mucinous neoplasm as a differential in the management of spontaneous right iliac fossa collections and fistulae.

Standardization of the pathologic diagnosis of appendiceal mucinous neoplasms

Although the understanding of appendiceal mucinous neoplasms (AMNs) and their relationship with disseminated peritoneal mucinous disease have advanced, the diagnosis, classification, and treatment of AMNs are still confusing for pathologists and clinicians. The Gastrointestinal Pathology Study Group of the Korean Society of Pathologists (GPSG-KSP) proposed a multicenter study and held a workshop for the “Standardization of the Pathologic Diagnosis of the Appendiceal Mucinous Neoplasm” to overcome the controversy and potential conflicts. The present article is focused on the diagnostic criteria, terminologies, tumor grading, pathologic staging, biologic behavior, treatment, and prognosis of AMNs and disseminated peritoneal mucinous disease. In addition, GPSG-KSP proposes a checklist of standard data elements of appendiceal epithelial neoplasms to standardize pathologic diagnosis. We hope the present article will provide pathologists with updated knowledge on how to handle and diagnose AMNs and disseminated peritoneal mucinous disease.

Incidental diagnosis of a low-grade mucinous appendicular neoplasm: A case report

INTRODUCTION AND IMPORTANCE

Low-Grade Appendiceal Mucinous Neoplasms (LAMN) are noninvasive epithelial tumors of the appendix. Symptomatology is unspecific and can simulate appendicitis. The multidisciplinary approach for the correct diagnosis and management of this kind of tumor is important, as the prognosis depends on it.

PRESENTATION OF THE CASE

A 70-years-old man with an appendiceal picture is presented. McBurney and Blumberg's signs were found and the Echography has reported an acute appendicitis. He underwent laparoscopic surgery, founding a Tumor in the Cecum of 10 × 5 cm. We decided to perform an appendectomy with a total cecectomy. The pathological diagnosis was a LAMN. Ten months later, a Computed Tomography (CT) Scan control was performed reporting no evidence of Tumoral activity or Distance Metastasis, neither pseudomyxoma peritonei (PMP) evidence.

DISCUSSION

LAMN has been a very controversial tumor. The definitive management is appendectomy. There are controversies about the laparoscopic and open approach, and when there are positive margins. The stage was a pTis (LAMN) pNx according to the 8th edition of the American Joint Committee on Cancer (AJCC). The prognosis depends on the tumoral stage and the presence of PMP. In our case, we have performed a CT scan follow up and there was no Tumoral activity or Distance Metastasis, neither PMP evidence.

CONCLUSION

LAMN is a very interesting and rare tumor. The diagnosis of this case was a real challenge. Our management was simple due to the tumoral stage. Pathology played a very important role in treatment and prognosis.

Epidemiology, histopathology, clinical outcomes and survival of 50 cases of appendiceal mucinous neoplasms: Retrospective cross-sectional single academic tertiary care hospital experience

Background

Appendicular neoplasms are rare, most commonly as carcinoids followed by appendicular mucinous neoplasms (AMN). To date, there remains controversy regarding the best treatment of AMN and factors affecting its prognosis.

Method

Retrospective chart review of patients operated for appendicular pathology (January 2011–December 2018, follow up to December 2020) at our institution. For all AMN patients, data included pre-operative clinical presentation, and operative/post-operative findings.

Results

12454 patients underwent appendectomy, of whom 50 (0.4%) had AMN histopathologically (mean age = 47.2). Most patients had laparoscopic appendectomy as primary surgery. Low grade AMN was the most common subtype (n = 41, 82%), and pseudomyxoma peritonei (PMP) was found in 8 (16%) patients. Based on histopathology and margin involvement, the 50 patients were categorized into 3 prognostic categories of recurrence risk (no risk, 24 patients; low risk, 8; high recurrence risk, 18 patients). Disease-free survival (DFS) was lowest for high recurrence risk group (P < 0.001). Eleven (22%) patients had AMN involving resection margin, of whom 3 had no completion surgery and had no recurrence. Higher tumor markers were associated with lower DFS, however it was not statistically significant.

Conclusion

AMNs are rare but serious due to the risk of PMP. Laparoscopic approach for AMN may be feasible. Prognostic categories were significantly inversely correlated with recurrence risk; hence useful in predicting prognosis. Contrary to previous proposals, AMNs with acellular mucin at margin or local acellular mucin spillage may not require secondary surgery, especially if the patient is in low recurrence risk group. Tumor markers may predict risk of recurrence.

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Laparoscopic approach may be feasible for appendiceal mucinous neoplasms (AMN).

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AMN can be categorized into 3 risk recurrence groups (No risk, low, and high).

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AMN with acellular mucin at the margin may not require secondary surgery.

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Higher tumor markers may indicate high risk of AMN recurrence.

High-grade appendiceal mucinous neoplasm presenting as a giant appendiceal mucocele

Appendiceal mucinous neoplasms are rare findings defined by an accumulation of mucus within the vermiform appendix, and can be caused by a variety of conditions. Appendiceal mucinous neoplasms are important to consider because they can develop into pseudomyxoma peritonei as a consequence of perforation. We report a case of a 55-year-old man who initially presented with increasing abdominal girth, constipation, anorexia, and unintentional weight loss. Computed tomography examination of the abdomen and pelvis demonstrated a huge thin-walled cystic mass causing significant displacement of the surrounding abdominal and pelvic structures. The mass was amenable to resection and removed without perforation. Gross pathologic examination demonstrated a 44.0 × 40.0 × 23.0 cm unilocular cystic mass with a section of attached bowel. Microscopic examination revealed high-grade appendiceal mucinous neoplasm arising in a background of low-grade appendiceal mucinous neoplasm. This case report provides an evidence to include appendiceal mucinous neoplasms in the differential diagnosis of large abdominal cystic masses.

Emergency laparoscopic ileocecal resection for a low-grade appendiceal mucinous neoplasm with impending rupture: A case report

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Appendiceal mucinous neoplasms account for less than 1% of all cancers.

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LAMNs have an aggressive biological potential.

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Preoperative diagnosis of appendiceal mucinous neoplasms is difficult.

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Here, we used emergency MRI to identify nodules in the appendix before operation.

Introduction and importance

We report the case of a patient with a low-grade appendiceal mucinous neoplasm (LAMN) who underwent emergency laparoscopic ileocecal resection to avoid the metastatic spread of tumor cells due to an impending rupture.

Case presentation

A 55-year-old woman presented to our hospital with pain in the right lower quadrant of the abdomen. Computed tomography revealed a markedly tense appendiceal mucinous tumor with surrounding inflammation, and laboratory test results showed elevated serum C-reactive protein (7.47 mg/dL), indicating impending rupture of the appendix. Magnetic resonance imaging revealed nodules inside the appendix, suggesting the possibility of appendiceal cancer. We performed emergency laparoscopic ileocecal resection with regional lymph node dissection. The tumor was pathologically diagnosed as a LAMN without rupture.

Clinical discussion

LAMN is classified as a clinically malignant tumor because it can cause pseudomyxoma peritonei due to perforation or the presence of residual tissue. Although an appendectomy would be appropriate for LAMN if the tumor margin is secured, ileocecal resection with lymph node dissection is necessary when preoperative discrimination of appendiceal cancer is impossible.

Conclusion

Further studies of preoperative imaging for appropriate differential diagnosis were necessary.

Single-incision laparoscopic surgery compared to conventional laparoscopic surgery for appendiceal mucocele: a series of 116 patients

BACKGROUND

Although the safety and feasibility of conventional laparoscopic surgery (CLS) for appendiceal mucocele (AM) has been reported, studies on single-incision laparoscopic surgery (SILS) for AM have not been reported. Here, we aimed to compare the perioperative and short-term outcomes between SILS and CLS for AM and to evaluate the oncological safety of SILS.

METHODS

We retrospectively analyzed the medical records of patients, diagnosed based on computed tomography findings, who underwent laparoscopic surgery for AM between 2010 and 2018 at one institution. We excluded patients strongly suspected of having malignant lesions and those with preoperative appendiceal perforation. Patients were divided into two groups-CLS and SILS. Pathological outcomes and long-term results were investigated. The median follow-up period was 43.7 (range: 12.3-118.5) months.

RESULTS

Ultimately, 116 patients (CLS = 68, SILS = 48) were enrolled. Patient demographic characteristics did not differ between the groups. The preoperative mucocele diameter was greater in the CLS than in the SILS group (3.2 ± 2.9 cm vs. 2.3 ± 1.4 cm, P = 0.029). More extensive surgery (right hemicolectomies and ileocecectomies) was performed in the CLS than in the SILS group (P = 0.014). Intraoperative perforation developed in only one patient per group. For appendectomies and cecectomies, the CLS group exhibited a longer operation time than the SILS group (63.3 ± 24.5 min vs. 52.4 ± 17.3 min, P = 0.014); the same was noted for length of postoperative hospital stay (2.9 ± 1.8 days vs. 1.7 ± 0.6 days, P < 0.001). The most common AM etiology was low-grade appendiceal mucinous neoplasm (71/116 [61.2%] patients); none of the patients exhibited mucinous cystadenocarcinoma. Among these 71 patients, there were 8 patients with microscopic appendiceal perforation or positive resection margins. No recurrence was detected.

CONCLUSIONS

SILS for AM is feasible and safe perioperatively and in the short-term and yields favorable oncological outcomes. Despite the retrospective nature of the study, SILS may be suitable after careful selection of AM patients.

Updated staging and patient outcomes in low-grade appendiceal mucinous neoplasms

Low-grade appendiceal mucinous neoplasms (LAMNs) exhibit drastically different clinical course and prognosis depending on tumor stage, particularly as it relates to the extent and cellularity of peritoneal involvement. In this context, recent changes in staging guidelines have sought to clarify criteria for pT and pM categories. This study's aim was to identify clinicopathological features associated with patient outcomes, especially as they pertain to updated stage groups. We reviewed LAMNs from 192 patients (mean age: 56.9 years, 119 (62.0%) women). The tumors consisted of 66 (34.4%) pTisM0, 16 (8.3%) pT3M0, 16 (8.3%) pT4aM0, 27 (14.1%) pTxM1a, and 67 (34.9%) pTxM1b cases. In multivariate analysis, only gross perforation was significantly associated with higher TNM group stage (p = 0.001; OR 3.3, 95% CI: 1.7-6.4). Of 165 (85.9%) patients with clinical follow-up, 51 (30.9%) had disease progression (over a mean 33.7 months, range: 4.7-121.7), whereas over significantly longer follow-up (mean 48.7 months, range: 3.1-143.9; p = 0.004), 114 (69.1%) patients did not. In multivariate analysis, higher TNM stage was significantly associated with disease progression (p = 0.029; OR 18.3, 95% CI: 1.4-246.0). In Kaplan-Meier analysis, none of 74 patients with disease limited to the appendix (pM0), 6 of 27 (22.2%) cases with peritoneal involvement by acellular mucin only (pM1a), and 45 of 64 (70.3%) tumors with intraperitoneal deposits containing neoplastic cells (pM1b) showed disease progression (p < 0.001). These differences in progression-free survival among TNM groups persisted when limiting the analysis to patients who had undergone successful cytoreductive surgery (p = 0.050). Finally, in four patients (all with pM1b disease) death was attributed to disease progression whereas there was no disease-specific mortality in the pM0 and pM1a groups (p = 0.020). These data support the designation of LAMNs with acellular peritoneal mucin as having an intermediate prognosis between cases limited to the appendix and those with intraperitoneal deposits containing neoplastic epithelium.

A general overview of mucocele of appendix

Mucocele of the appendix is a very rare disease entity that often discovered incidentally during surgery. It can result from both non-neoplastic and neoplastic lesions and histopathological examination is needed for confirmation. Failure to make an early preoperative diagnosis may results in its rapture and spillage of mucin contents into the peritoneal cavity leading to a disastrous complication of pseudomyxoma peritonei (PMP) that has a very bad prognosis. A clear pathological terminology and management strategies of appendiceal mucocele (AM) is lacking. This literature review aims to derive detailed information related to clinical significance of AM to avoid complication of PMP and plan appropriately during surgery according to the current evidence. The relevant articles from scientific databases such as Medline, PubMed, Google Scholar were searched and extracted using the keywords “mucocele appendix” “cystadenoma%”. Data based on epidemiology, clinical manifestations, complications, pathology, diagnostic work up and management were analyzed and summarized. A meticulous surgical excision is the mainstay of treatment and open surgical approach is still preferred over laparoscopy. Preoperative diagnosis of AM is very imperative as it may harbour neoplasm and can be made utilising the imaging tools like computed tomography and ultrasonography. Primary care physicians can have a crucial role in making early detection and timely referral for appropriate management in order to avoid complications. After appendectomy, 5-year survival rate for the simple AM is 91%-100% but it reduces to 25% for the malignant AM.

Germline and somatic genetic alterations in two first-degree relatives with appendiceal low-grade mucinous carcinoma peritonei

Comparing genetic mutations of first-degree relatives with appendiceal pseudomyxoma peritonei may explain clinical outcomes and disease pathogenesis. Molecular profiling of mucinous tumors may identify improved treatments to traditional chemotherapy.

Primary Appendiceal Adenocarcinoma Presenting with Hematochezia due to the Invading Tumor in the Sigmoid Colon

Primary appendiceal tumors are rare malignancies; some cases have been described to invade other organs, and this represents a very rare clinical condition. We report a case of appendiceal adenocarcinoma invading the sigmoid colon and a review of similar cases. A 69-year-old woman with complaints of hematochezia was admitted to the hospital. Colonoscopy revealed a tumor in the sigmoid colon, which was a well-differentiated tubular adenocarcinoma. A computed tomography scan showed an appendiceal mass that involved the sigmoid colon, suggesting an appendiceal cancer invading the sigmoid colon. Ileocecal resection with extended lymphadenectomy and en bloc resection of the sigmoid colon was performed. The appendiceal tumor involved the sigmoid colon and the terminal ileum. The ileocecal part which included the tumor and the involved sigmoid colon was resected in total. Macroscopic findings showed that the appendiceal tumor made a fistula with the sigmoid colon. Pathological examination revealed that the tumor was a well-differentiated tubular adenocarcinoma that invaded the sigmoid colon. The final pathological stage was T4bN0M0, stage IIC. The patient was discharged from the hospital uneventfully. She was alive without relapse after a 20-month follow-up. Although an appendiceal tumor invading the rectosigmoid region is rare, a preoperative diagnosis can be obtained that facilitates the planning of a suitable surgical procedure: en bloc resection of the ileocecal part and the rectosigmoid part.

Defining "Complete Cytoreduction" After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (CRS/HIPEC) for the Histopathologic Spectrum of Appendiceal Carcinomatosis

BACKGROUND

The completeness of cytoreduction (CC) score, which quantifies residual tumor, is a major prognostic factor when treating appendiceal carcinomatosis with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). Both CC-0 and CC-1 are considered complete cytoreductions (CC-0/1) and associated with the best outcomes. We analyzed if the CC-0/1 definition is reliable across appendiceal histopathologic subtypes.

METHODS

A prospective database of CRS/HIPEC patients with appendiceal carcinomatosis from 1998 to 2019 was reviewed to identify patients with CC-0/1. Kaplan-Meier overall survival (OS) and progression-free survival (PFS) by CC-score for each histopathology were calculated.

RESULTS

Overall, 297 patients had CC-0/1. Mean age was 54 ± 12 years with 67% females. Histopathologic subtypes were 45% low-grade mucinous carcinoma peritonei (LGMCP), 27% high-grade MCP (HGMCP), 20% HGMCP with signet ring cells (HGMCP-S), and 8% goblet cell adenocarcinoma (GCAC). CC-0 and CC-1 occurred in 57% and 43% of LGMCP, 65% and 35% of HGMCP, 68% and 32% of HGMCP-S, and 79% and 21% of GCAC, respectively. OS and PFS were statistically longer for CC-0 versus CC-1 in HGMCP-S (p = 0.001 and p = 0.005, respectively) and GCAC (p < 0.001 and p < 0.001), but not in LGMCP (p = 0.098 and p = 0.398) or HGMCP (p = 0.167 and p = 0.356).

CONCLUSIONS

Survival outcomes for CC-0 and CC-1 after CRS/HIPEC are different for HGMCP-S and GCAC but not for LGMCP and HGMCP. In HGCMP-S and GCAC, only CC-0 should be considered a complete cytoreduction and analyzed separately from CC-1. This distinction is key to understand disease behavior, accurately address patient prognosis, and explore new treatment strategies.

Local Protocol for Management of Low-Grade Appendiceal Mucinous Neoplasm (LAMN)

The management and surveillance of low-grade appendiceal mucinous neoplasm (LAMN) is a confusing topic in the colorectal MDM. This study was aiming to provide a local protocol for our trust for such cases. From prospectively maintained database, patients who underwent appendicectomy between 2011 and 2017 were identified. Those with histological confirmation of LAMN were included. Retrospective analysis of operative notes, investigations and follow-up, return to theatres or development of pseudomyxoma peritonei (PMP) was performed. Four thousand six hundred twenty-eight patients had appendicectomy; 36 were diagnosed with LAMN. Age range was 30-88 (20 females). Fifteen had their operation as emergency and 13 elective, either for abnormal-looking appendix on CT scan or as part of elective right hemicolectomy. In 8 patients, LAMNs were diagnosed incidentally during other surgery either intraoperatively or on histology. Two patients had mucus in the peritoneal cavity (not sampled). The remaining 34 had either contained mucocele or inflamed appendix. Regarding follow-up, 28 patients had CT scans only, and 2 had ultrasound scan (USS). Two had both CT and USS. Three had CT and MRI scans. One patient did not have radiological investigations. Eighteen patients had colonoscopies (50%). Three patients had no follow-up, while 33 had 5-year follow-up. Ten patients are still currently under follow-up. None of the 36 patients required further surgeries related to LAMN, and none has developed PMP to date of the study. We have developed a local protocol based on our findings and literature review for management and surveillance of LAMN in line with national centres.

Improved Outcome Prediction for Appendiceal Pseudomyxoma Peritonei by Integration of Cancer Cell and Stromal Transcriptional Profiles

In recent years, cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) have substantially improved the clinical outcome of pseudomyxoma peritonei (PMP) originating from mucinous appendiceal cancer. However, current histopathological grading of appendiceal PMP frequently fails in predicting disease outcome. We recently observed that the integration of cancer cell transcriptional traits with those of cancer-associated fibroblasts (CAFs) improves prognostic prediction for tumors of the large intestine. We therefore generated global expression profiles on a consecutive series of 24 PMP patients treated with CRS plus HIPEC. Multiple lesions were profiled for nine patients. We then used expression data to stratify the samples by a previously published “high-risk appendiceal cancer” (HRAC) signature and by a CAF signature that we previously developed for colorectal cancer, or by a combination of both. The prognostic value of the HRAC signature was confirmed in our cohort and further improved by integration of the CAF signature. Classification of cases profiled for multiple lesions revealed the existence of outlier samples and highlighted the need of profiling multiple PMP lesions to select representative samples for optimal performances. The integrated predictor was subsequently validated in an independent PMP cohort. These results provide new insights into PMP biology, revealing a previously unrecognized prognostic role of the stromal component and supporting integration of standard pathological grade with the HRAC and CAF transcriptional signatures to better predict disease outcome.

Impact of Mucin Cellularity and Distribution on Survival in Newly Diagnosed Patients with Low-Grade Appendiceal Mucinous Neoplasm Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

BACKGROUND

Low-grade appendiceal mucinous neoplasms (LAMN) are tumors that frequently present with peritoneal spread of either acellular mucin (AM) or cellular mucin (CM). We aim to determine how mucin types and distribution affect survival. PATIENTS AND METHODS: A retrospective cohort study was conducted using a prospective database. Newly diagnosed LAMN patients with AM versus CM treated with cytoreductive surgery/hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) were compared. Postoperative pathology reports were reviewed to assess each involved abdominal zone. Survival was analyzed using the Kaplan-Meier method.

RESULTS

Of 121 identified patients, 50 (41%) had peritoneal lesions with AM and 71 (59%) with CM. Peritoneal cancer index was lower in AM versus CM (mean: 19 ± 13 vs 28 ± 10, p = 0.004), but complete cytoreduction (CC) rates were similar (98% vs 96%, p = 0.642). The 5-year progression-free survival (PFS) was higher in AM versus CM (96% vs 69.8%, p = 0.002). CM patients had zones with both types of lesions: with and without cells. The CM subgroup analysis showed significant differences in 5-year progression-free survival (PFS) among patients with 1-3, 4-7, and 8-10 zones with cells (95.2%, 68.4%, and 35.7%, respectively, p < 0.001), but PFS was not affected by the number of zones with any lesion type. There was no difference in overall survival (OS) between groups.

CONCLUSIONS

Despite comparable CC rates after CRS/HIPEC, CM patients have shorter PFS than AM patients. In CM patients, more zones with cells, but not the total number of involved zones, negatively impact PFS. Mucin type does not impact OS. It is important to assess and report mucin cellularity in LAMN specimens.

Germline whole exome sequencing of a family with appendiceal mucinous tumours presenting with pseudomyxoma peritonei

Background

Familial cases of appendiceal mucinous tumours (AMTs) are extremely rare and the underlying genetic aetiology uncertain. We identified potential predisposing germline genetic variants in a father and daughter with AMTs presenting with pseudomyxoma peritonei (PMP) and correlated these with regions of loss of heterozygosity (LOH) in the tumours.

Methods

Through germline whole exome sequencing, we identified novel heterozygous loss-of-function (LoF) (i.e. nonsense, frameshift and essential splice site mutations) and missense variants shared between father and daughter, and validated all LoF variants, and missense variants with a Combined Annotation Dependent Depletion (CADD) scaled score of ≥10. Genome-wide copy number analysis was performed on tumour tissue from both individuals to identify regions of LOH.

Results

Fifteen novel variants in 15 genes were shared by the father and daughter, including a nonsense mutation in REEP5. None of these germline variants were located in tumour regions of LOH shared by the father and daughter. Four genes (EXOG, RANBP2, RANBP6 and TNFRSF1B) harboured missense variants that fell in a region of LOH in the tumour from the father only, but none showed somatic loss of the wild type allele in the tumour. The REEP5 gene was sequenced in 23 individuals with presumed sporadic AMTs or PMP; no LoF or rare missense germline variants were identified.

Conclusion

Germline exome sequencing of a father and daughter with AMTs identified novel candidate predisposing genes. Further studies are required to clarify the role of these genes in familial AMTs.