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

Incidental appendiceal mucocele discovery: A case series and literature review

INTRODUCTION

Low-grade appendiceal mucinous neoplasms (LAMNs) are rare entities that can present significant challenges when discovered incidentally by general surgeons during surgery or through postoperative pathology. These lesions may mimic common abdominal conditions and are often not suspected preoperatively.

METHODS

We present a case series of five patients in whom appendiceal mucoceles were incidentally identified either intraoperatively or on postoperative pathological examination. The patients ranged from 36 to 79 years old and presented with symptoms such as right lower quadrant pain, initially attributed to appendicitis, ovarian torsion, or other gynecological conditions. Intraoperative findings varied from dilated appendices with mucinous content to large cystic masses involving adjacent structures.

RESULTS

In each case, the general surgeon had to make immediate decisions regarding management. Surgical interventions included laparoscopic appendectomy and open right hemicolectomy, with an emphasis on careful handling to prevent rupture and spillage of mucin. Postoperative pathology confirmed LAMNs, with tumor stages ranging from pTis to pT4a. Some patients required additional procedures, such as cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC), due to the presence of acellular mucin or peritoneal involvement. The discussion focuses on practical guidance for general surgeons when faced with an incidental appendiceal mucocele. Key recommendations include avoiding intraoperative rupture by gentle handling, assessing the need for extended resection based on intraoperative findings, and ensuring thorough communication with pathology for accurate staging. Postoperative management should involve reviewing pathology reports carefully, considering referral to a multidisciplinary team for higher-stage tumors, and implementing long-term surveillance protocols due to the risk of recurrence.

CONCLUSION

General surgeons play a critical role in the initial management of incidentally discovered appendiceal mucoceles. Prompt recognition and appropriate intraoperative decision-making are essential to optimize patient outcomes. By adhering to careful surgical techniques and collaborating with multidisciplinary teams, surgeons can effectively manage these unexpected findings and mitigate potential complications associated with LAMNs.

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.

Low-grade appendiceal mucinous neoplasm: A case report

RATIONALE

Low-grade appendiceal mucinous neoplasm (LAMN) is a clinically rare tumor that predominantly occurs in females and presents with nonspecific symptoms, often resulting in misdiagnosis. While postoperative pathology remains the gold standard for diagnosis, accurate preoperative identification through various diagnostic methods is essential for effective treatment planning. To raise awareness of this condition, we present a case of a middle-aged male diagnosed with LAMN.

PATIENT CONCERNS

A 52-year-old male presented to outpatient clinic with right lower abdominal pain lasting 1 day. He described the pain as continuous cramping, exacerbated by movement and coughing, with associated nausea.

DIAGNOSIS

Physical examination revealed tenderness in the right lower quadrant and a palpable mass measuring approximately 6.5 cm × 5.0 cm, with poor definition and limited mobility. An elevated white blood cell count (16.2 × 109/L) and a mixed cystic and solid mass were noted, prompting admission for further evaluation. Further, abdominal enhanced computed tomography revealed a mixed-density lesion in the right ileocecal region, measuring approximately 6.5 cm × 5.0 cm. This finding was suggestive of an appendiceal mucinous neoplasm, with mucinous adenocarcinoma remaining a possibility that could not be excluded.

INTERVENTIONS

The patient underwent a laparoscopic right hemicolectomy on June 5, 2024, and the gross specimen showed: a 6.5 cm × 5.0 cm mass was found in the appendix area on the surface of the intestinal tube, a large amount of jelly was found after incision, and the mass was connected to the intestinal cavity.

OUTCOMES

The patient recovered well after surgery, the abdominal drainage tube was pulled out on the 8th day after surgery, and the patient was discharged on the 13th day after surgery. Postoperative examination showed LAMN and mucus accumulation in the wall of the appendix with a foreign body giant cell reaction, acute attack of chronic appendicitis, and suppurative inflammation with peripheral inflammation. Postoperative diagnosis: LAMN; acute chronic appendicitis attack.

LESSONS

As a rare clinical gastrointestinal tumor, LAMN lacks specific clinical manifestations, and its diagnosis depends on postoperative examination; however, the indications for surgery are clear and the clinical prognosis is good. The key to surgery is to protect the tumor body to avoid rupture and cause the development of peritoneal pseudomyxoma (PMP).

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.

Is Hyperthermic Intraperitoneal Chemotherapy Appropriate for Colon Cancer?

Colorectal cancer (CRC) with peritoneal metastases is a complex disease and its management presents significant clinical challenges. In well-selected patients at experienced centers, CRS/hyperthermic intraperitoneal chemotherapy (HIPEC) can be performed with acceptable morbidity and is associated with prolonged survival. Based on the results of recent randomized controlled trials, HIPEC using oxaliplatin after CRS with shortened perfusion periods (30 minutes) is no longer recommended. There is a movement toward utilizing mitomycin C as a first-line intraperitoneal agent with extended perfusion times (90-120 minutes); however, there is currently little prospective evidence to support its widespread use.

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.

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.