Progression to pseudomyxoma peritonei in patients with low grade appendiceal mucinous neoplasms discovered at time of appendectomy

Low-grade appendiceal mucinous neoplasms: a case series

Appendiceal mucinous neoplasms, including low-grade appendiceal mucinous neoplasms (LAMNs), are infrequent but clinically relevant due to their potential progression to pseudomyxoma peritonei. Timely diagnosis and surgical intervention are critical to preventing complications. We present a case series of three middle-aged men with LAMNs, each of whom exhibited right lower quadrant abdominal pain as their primary symptom. Diagnostic imaging in each case revealed features consistent with appendiceal mucoceles. Pathological findings confirmed LAMN, with varying extents of disease. One patient underwent an open appendectomy for LAMN confined to the appendix, while two required right hemicolectomy due to perforation and extra-appendiceal mucin involvement. LAMNs can be managed effectively through early detection and surgical resection. Complete resection with negative margins results in favorable outcomes and low recurrence rates. More aggressive treatments, including cytoreductive surgery with or without hyperthermic intraperitoneal chemotherapy, are necessary in cases with peritoneal involvement.

A scoping review of postoperative surveillance strategies for localized, low-grade appendiceal mucinous neoplasms

INTRODUCTION

There is a paucity of data to support surveillance protocols for localized, low-grade appendiceal mucinous neoplasms (LAMNs) after resection.

METHODS

A search strategy was developed to identify postoperative surveillance strategies for LAMNs, in the context of rates of recurrence and disease-free survival, and applied to four literature databases. Resultant citations were subject to screening in duplicate, in three stages: title, abstract, and full-text. Data was extracted from the final set of included articles and subject to descriptive statistics.

RESULTS

A total of 16 articles, representing 1218 patients, were included. The duration of surveillance ranged from 0.1 to 294 months, and the mode surveillance interval was three months. The most common surveillance method was imaging (n ​= ​610 patients, 48.7 ​%). Thirty one patients had disease recurrence (2.7 ​%). Time to recurrence ranged from 2.5 to 68 months, and the range of five-year survival was 93.5-95.2 ​% among five studies.

DISCUSSION

In the absence of strong evidence to suggest that surveillance confers a survival benefit for patients with localized LAMNs after resection, decisions about surveillance should be patient-oriented.

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.

Molecular Profiling of Low-Grade Appendiceal Mucinous Neoplasms (LAMN)

Low-grade appendiceal mucinous neoplasia (LAMN) represents a relatively rare tumor of the appendix typically diagnosed incidentally through appendectomy for acute appendicitis. In cases where perforation occurs, mucinous content may disseminate into the abdominal cavity, leading to the development of pseudomyxoma peritonei (PMP). The primary objective of this study was to elucidate the molecular characteristics associated with various stages of LAMN and PMP. DNA was extracted from LAMN, primary PMPs, recurrent PMPs, and adenocarcinomas originating from LAMN. The subsequent analysis involved the examination of mutational hotspot regions within 50 cancer-related genes, covering over 2800 COSMIC mutations, utilizing amplicon-based next-generation sequencing (NGS). Our findings revealed activating somatic mutations within the MAPK-signaling pathway across all tumors examined. Specifically, 98.1% of cases showed mutations in KRAS, while one tumor harbored a BRAF mutation. Additionally, GNAS mutations were identified in 55.8% of tumors, with no significant difference observed between LAMN and PMP. While LAMN rarely displayed additional mutations, 42% of primary PMPs and 60% of recurrent PMPs showed additional mutations. Notably, both adenocarcinomas originating from LAMN showed mutations within TP53. Furthermore, 7.7% (4/52) of cases exhibited a potentially targetable KRAS G12C mutation. In four patients, NGS analysis was performed on both primary PMP and recurrent PMP/adenocarcinoma samples. While mutations in KRAS and GNAS were detected in almost all samples, 50% of recurrent cases displayed an additional SMAD4 mutation, suggesting a notable alteration during disease progression. Our findings indicate two key points: First, mutations within the MAPK pathway, particularly in KRAS, are evident across all tumors, along with a high frequency of GNAS mutations. Second, progression toward PMP or adenocarcinoma is associated with an accumulation of additional mutations within common oncogenic pathways.

Low-grade Appendiceal Mucinous Neoplasm with Appendiceal Reduction and Re-expansion Over a Two-year Period

A 71-year-old woman was found to have submucosal tumor-like lesion on colonoscopy (CS) before gastric surgery, and computed tomography (CT) showed a 12-mm structure at the base of the appendix. The lesion could not be clearly detected on CT nine months later, but it had enlarged again on CT one year later; therefore, CS and endoscopic ultrasound (EUS) were performed. The lesion was determined to be cystic with viscous contents, and laparoscopic appendicectomy was performed. This is the first report of low-grade appendiceal mucinous neoplasm (LAMN) diagnosed by a histopathologic examination of a resected specimen showing shrinkage and re-expansion of the appendix.

Appendiceal neoplasms derived from appendiceal tip remnants following appendectomy: a report of two cases

BACKGROUND

Neoplasms derived from remnant appendix are rarely described, with most cases arising from the appendiceal "stump". Here, we present two surgical cases of appendiceal neoplasms derived from appendiceal "tip" remnants.

CASE PRESENTATION

The first patient was a 71-year-old man who had undergone laparoscopic appendectomy for acute appendicitis 12 years prior. During appendectomy, the appendiceal root was ligated, but the appendix was not completely removed due to severe inflammation. At the most recent presentation, computed tomography (CT) was performed to examine choledocholithiasis, which incidentally revealed a cystic lesion of approximately 90 mm adjacent to the cecum. A retrospective review revealed that the cystic lesion had increased in size over time, and laparoscopic ileocecal resection was performed. Pathology revealed no continuity from the appendiceal orifice to the cyst, and a diagnosis of low-grade appendiceal mucinous neoplasm (LAMN) was made from the appendiceal tip remnant. The patient was discharged without complications. The second patient was a 65-year-old man who had undergone surgery for peritonitis due to severe appendicitis 21 years prior. During this operation, the appendix could not be clearly identified due to severe inflammation; consequently, cecal resection was performed. He was referred to our department with a chief complaint of general fatigue and loss of appetite and a cystic lesion of approximately 85 mm close to the cecum that had increased over time. CT showed irregular wall thickening, and malignancy could not be ruled out; therefore, laparoscopic ileocecal resection with D3 lymph node dissection was performed. The pathological diagnosis revealed mucinous adenocarcinoma (TXN0M0) arising from the remnant appendiceal tip. The patient is undergoing follow-up without postoperative adjuvant chemotherapy, with no evidence of pseudomyxoma peritonei or cancer recurrence for 32 months postoperatively.

CONCLUSIONS

If appendicitis-associated inflammation is sufficiently severe that accurate identification of the appendix is difficult, it may remain on the apical side of the appendix, even if the root of the appendix is ligated and removed. If the appendectomy is terminated incompletely, it is necessary to check for the presence of a residual appendix postoperatively and provide appropriate follow-up.

Neoplastic appendiceal mucinous lesions: a narrative review of the literature from an oncologist's perspective

Appendiceal mucinous lesions' classification and nomenclature has been modified several times along the last decades, reflecting their great heterogeneity and making difficult to compare results and draw conclusions. Despite its nearby origin, appendiceal mucinous lesions have a distinctive behaviour compared to colorectal cancer, including their molecular and genetic markers. Due to their low frequency, their management is not well standardised. However, surgery is considered the cornerstone of treatment. Their indolent behaviour has encouraged surgeons to apply more aggressive treatments, such as cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC), that may extend overall survival. Chemotherapy is reserved for unresectable and/or disseminated disease and could play a role in the adjuvant and neoadjuvant setting. Pressurised intraperitoneal aerosol chemotherapy (PIPAC) is recently emerging as a possible alternative for treatment in advanced disease although its results in long-term survival are lacking Hereby, we review the available evidence in the management of appendiceal mucinous lesions, including localised and disseminated disease, with a special emphasis on the oncological perspective, focusing on the lights and shadows of the systemic treatments.

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.

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.

A Case of Low-Grade Appendiceal Mucinous Neoplasm That Led to Surgery After 12 Years of No Treatment

Low-grade appendiceal mucinous neoplasm (LAMN) is a relatively rare, non-invasive appendiceal tumor. We experienced a case of LAMN that led to surgery after 12 years of no treatment. Until now, LAMN has been reported to progress more slowly than other tumors, but there have been no reports of long-term follow-up of appendiceal tumors without treatment. Although the tumor had grown over the course of 12 years, there was no mixing or migration of other histological types, and it did not lead to pseudomyxoma peritonei. As this course is considered to be relatively rare, we report it along with a literature review.

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.

Clinicopathological Characteristics of Primary Appendiceal Mucinous Neoplasm and Recurrence After Radical Resection

Objective

Appendiceal mucinous neoplasm (AMN) is a rare obstructive dilatation of the appendix caused by an intraluminal accumulation of mucoid material, showing an insidious onset and few specific clinical manifestations. The purpose of the study is to analyze clinicopathological characteristics of primary AMN and recurrence after radical resection.

Methods

A total of 50 patients were included in the retrospective cohort study of AMN. Patient data, such as demographics, tumor characteristics, surgical management, preoperative serum carcinoembryonic antigen (CEA), and carcinoembryonic antigen 19-9 (CA19-9) levels, were collected. All patients were followed-up with interval CT scans until the end of December 2021, with overall survival (OS) and progression-free survival (PFS) being calculated.

Results

All patients were confirmed as AMN by pathological diagnosis after surgery, including 28 cases (56.00%) of low-grade AMN (LAMN) and 22 cases (44.00%) of non-LAMN. Among 50 patients with AMN, there were 12 cases (24.00%) complicated with pseudomyxoma peritonei (PMP). Higher proportions of patients with pTis, pT3, pT4a, ruptured at presentation, and PMP were found in patients with non-LAMN patients than LAMN (p < 0.05). There was a remarkable difference about preoperative serum CA19-9 levels between patients with LAMN and non-LAMN (p = 0.044). Patients complicated with PMP had a higher proportion of patients with ruptured at presentation than those who were not (p < 0.001). The patients with PMP had increased tumor size compared with those without PMP (p = 0.031). Remarkable differences were observed in terms of preoperative serum CA19-9 (p = 0.009) levels between patients with PMP and without PMP. We performed a multivariate analysis of the presence or absence of PMP and found that ruptured at presentation was found to be a risk factor for PMP in patients with AMN (p = 0.003). The PFS in the patients with PMP and those without was 33.33% (4/12) and 2.63% (1/38), showing a significant difference (P = 0.002).

Conclusion

The study demonstrates that ruptured at presentation and PMP may influence the prognosis and survival of patients with AMN.