Management of Low-Grade Appendiceal Mucinous Neoplasms (LAMN): An International Survey of Surgeons Performing CRS and HIPEC

Lower Gastrointestinal Bleeding Secondary to Appendiceal Mucinous Neoplasm: A Report of Two Cases and a Review of the Literature

Appendicular mucinous neoplasms, constituting less than 1% of gastrointestinal tract neoplasms, are heterogeneous entities. They may be asymptomatic, discovered incidentally, or present as large tumors due to mucin accumulation. The lack of standardized treatment complicates management. Imaging studies, particularly CT scans, are crucial for diagnosis and follow-up. This case report presents two clinical cases of women in their sixth and seventh decades of life with a history of lower gastrointestinal bleeding, mild anemia in laboratory studies, and incomplete colonoscopies. The diagnosis, confirmed through CT scans, led to the decision for surgical intervention in both cases, involving laparoscopic right hemicolectomy with ileotransverse anastomosis. Subsequently, histopathological reports confirmed the diagnosis of high-grade appendicular mucinous neoplasms, and a follow-up plan was established with imaging studies every six months with no recurrence at two years. Over 50% of appendicular tumors are mucinous neoplasms originating from low-grade mucinous neoplasms. Given the low lymph node invasion (2%), appendectomy may suffice if the entire tumor is excised. Extensive resections or right hemicolectomy are reserved for larger tumors or high-grade neoplasms to minimize local recurrence risk. Mucinous neoplasms with acellular mucin and peritoneal invasion may require cytoreduction or right hemicolectomy, while those with mucinous epithelium may need hyperthermic intraperitoneal chemotherapy (HIPEC) due to the risk of local recurrence, worsened by the presence of extra appendiceal epithelial cells. Disease-free and overall survival depend on treatment and initial lesion characterization. A five-year survival rate of 86% is reported for low-grade mucinous neoplasms. Follow-up approaches lack an ideal standard, generally involving physical examinations and imaging studies every six months to one year during the first six years.

Treatment Variation and Long-Term Outcomes of Low-Grade Appendiceal Neoplasms

BACKGROUND

Heterogenous nomenclature describing appendiceal neoplasms has added to uncertainty around their appropriate treatment. Although a recent consensus has established the term low-grade appendiceal neoplasm (LAMN), we hypothesize that significant variation remains in the treatment of LAMNs.

METHODS

We retrospectively reviewed our prospectively maintained appendiceal registry, identifying patients with LAMNs from 2009 to 2019. We assessed variability in treatment, including whether patients underwent colectomy, spread of disease at presentation, and long-term outcomes.

RESULTS

Of 136 patients with LAMNs, 88 (35%) presented with localized disease and 48 (35%) with disseminated peritoneal disease. Median follow-up was 2.9 years (IQR 1.9-4.4), and 120 (88%) patients underwent pre-referral surgery. Among 26 pre-referral colectomy patients, 23 (88%) were performed for perceived oncologic need/nodal evaluation; no nodal metastases were identified. In patients with resected LAMNs without radiographic evidence of disseminated disease, 41 (47%) underwent second look diagnostic laparoscopy (DL) to evaluate for occult metastases. No peritoneal metastases were identified. Patients with disseminated disease were treated with cytoreductive surgery/heated intraperitoneal chemotherapy (CRS/HIPEC). For patients undergoing CRS/HIPEC, 5-year recurrence-free survival was 94% (95% CI 81-98%). For patients with localized disease, 5-year RFS was 98% (95% CI 85-99%).

CONCLUSIONS

Significant variation exists in treatment patterns for LAMNs, particularly prior to referral to a high-volume center. Patients frequently underwent colectomy without apparent oncologic benefit. In the current era of high-quality cross sectional imaging, routine use of DL has low yield and is not recommended. Recurrence in this population is rare, and low-intensity surveillance can be offered. Overall prognosis is excellent, even with peritoneal disease.

Outcomes of laparoscopic single-incision caecal pole resection for low-grade appendiceal mucinous neoplasm

Introduction

Low-grade appendiceal mucinous neoplasm (LAMN) is a rare disease, and its clinical course varies from an incidental finding without symptoms to pseudomyxoma peritonei. Furthermore, there are few established treatment guidelines. This study was designed to confirm the outcomes in patients diagnosed with LAMN who underwent single-incision laparoscopic caecal pole resection.

Patients and Methods

This study was conducted on pathologically confirmed LAMNs from patients who underwent surgery at a single centre, a tertiary institution, from July 2016 to August 2022. Patients diagnosed with LAMN as a result of biopsy were included. All surgeries were performed with single-incision laparoscopic caecal pole resection by a single surgeon.

Results

A total of 70 patients were included. The median age was 65.5 years and 36 (51.4%) patients were female. The baseline carcinoembryonic antigen (CEA) was 8.08 ng/mL (0.76-148.11). The mean maximum diameter was 29.4 mm (7-70) and calcification was seen in 22 cases on pre-operative computed tomography (CT). As a result of histological examination, all patients were marginally negative. The larger the tumour size, the higher the CEA was (P = 0.011), and it was often accompanied by calcification (P = 0.021). In addition, tumour size and CEA showed a positive partial correlation with each other (r = 0.318, P = 0.018). The overall median follow-up period was 22.7 months (2-60). One case had suspected of recurrence on CT scan performed at 33 months following the surgery, but there were no related symptoms.

Conclusion

Single-port laparoscopic caecal pole resection without margin involvement in LAMN was safe and feasible, and showed a favourable long-term outcome.

Neoplasias apendiculares incidentales

Las neoplasias apendiculares se presentan hasta en el 50 % de los casos como un episodio de apendicitis aguda. Existen características demográficas, clínicas y radiológicas que aumentan las posibilidades de un tumor apendicular subyacente, sin embargo, en la mayoría de los casos, son los hallazgos intraoperatorios los que alertan al cirujano. A pesar de que el tipo histológico determina la radicalidad del manejo quirúrgico de estos pacientes, algunas características macroscópicas pueden orientar a las patologías específicas y a una conducta adecuada. En general, los objetivos del manejo quirúrgico inicial se cumplen con una resección limitada al apéndice cecal, asociada a la citología de mucina y biopsia de los implantes peritoneales si están presentes, reservando las resecciones extendidas, como hemicolectomía derecha oncológica, para los pacientes con compromiso extenso de la base o del mesenterio apendicular ante la sospecha de neoplasias neuroendocrinas o adenocarcinoma del apéndice cecal.

Novel Perspectives in Pseudomyxoma Peritonei Treatment

Simple Summary

Pseudomyxoma Peritonei (PMP) represents a rare entity which greatly benefits from Cytoreductive Surgery (CRS) associated with Hyperthermic Intraperitoneal Chemotherapy (HIPEC). In fact, CRS-HIPEC represents the treatment with potential chances of cure and long-term disease control of patients affected by PMP. This therapeutic strategy should be performed in referral centers, where a consolidated know-how of this locoregional treatment and a multidisciplinary approach are available. CRS-HIPEC provides excellent results for PMP patients in terms of postoperative outcome, overall and disease-free survival, and quality of life. However, in patients with an extensive or recurrent disease, few therapeutic opportunities are available. This review is focused on the most recent clinical evidence and provides a better understanding of the molecular prognostic factors and potential therapeutic targets in this rare malignancy.

Abstract

Pseudomyxoma Peritonei (PMP) is an anatomo-clinical condition characterized by the implantation of neoplastic cells on peritoneal surfaces with the production of a large amount of mucin. The rarity of the disease precludes the evaluation of treatment strategies within randomized controlled trials. Cytoreductive Surgery (CRS) combined with Hyperthermic Intraperitoneal Chemotherapy (HIPEC) has proven to be the only therapeutic option with potential chances of cure and long-term disease control. The present review discusses the epidemiology, pathogenesis, clinical presentation and treatment of PMP, focusing on the molecular factors involved in tumor progression and mucin production that could be used, in the upcoming future, to improve patient selection for surgery and to expand the therapeutic armamentarium.