Managing Pseudomyxoma Peritonei (Jelly Belly): Surgery, HIPEC & More

Introduction

Pseudomyxoma peritonei (PMP) is a rare yet significant malignant abdominal condition with an estimated incidence of approximately 2 per million people annually.

The rarity of PMP has contributed to delayed recognition and limited awareness among both patients and clinicians. Notably, actress Audrey Hepburn was believed to have had a form of abdominal cancer consistent with PMP, and her son, Sean Hepburn Ferrer, has since supported rare disease advocacy efforts. Former professional rugby player Steve Prescott was another prominent figure diagnosed with PMP in 2006 who later established a foundation to raise awareness and support fundraising efforts before his passing in 2013.

PMP requires a specialized, multimodal treatment strategy because standard systemic chemotherapy alone is often ineffective. The disease typically involves multiple peritoneal surfaces, making complete management complex. Optimal care, therefore, relies on multidisciplinary teams experienced in the management of peritoneal surface malignancies.

Over the past few decades, outcomes have significantly improved with the adoption of cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). This combined approach has transformed PMP from a highly fatal condition into one where long-term survival is achievable for many patients.

What Is Pseudomyxoma Peritonei?

Pseudomyxoma peritonei is a rare abdominal disease in which mucin-producing tumor cells accumulate within the peritoneal cavity. These cells continuously secrete thick, gelatinous mucus that gradually fills the abdomen, a presentation often described as “jelly belly.” Unlike many cancers that spread rapidly through the bloodstream, PMP typically progresses within the abdominal cavity itself.

PMP usually begins when a mucinous tumor ruptures, releasing epithelial cells into the peritoneal cavity. Once implanted on peritoneal surfaces, these cells continue producing mucin. Over time, the accumulating mucus compresses abdominal organs, interferes with bowel function, and increases abdominal girth.

A key biological feature of PMP is the redistribution phenomenon. Tumor cells circulate with peritoneal fluid and preferentially implant in gravity-dependent and fluid-absorbing areas. Common sites include the omentum, pelvis, diaphragm surfaces, liver capsule, spleen, and bowel lining.

Prevalence: Gender and Age

PMP is diagnosed slightly more often in women, partly because ovarian involvement was historically thought to be the primary source. Most patients are diagnosed between the ages of 40 and 60, though cases can occur outside this range. Diagnosis is often delayed because symptoms develop gradually.

Origin and Causes

In most cases, PMP originates from appendiceal mucinous tumors, particularly low-grade appendiceal mucinous neoplasms (LAMNs). When the appendix ruptures, tumor cells seed the peritoneal cavity.

Ovarian involvement is frequently secondary to an appendiceal source. However, rare primary ovarian mucinous tumors, especially mucinous borderline tumors, have been associated with PMP. Extremely rare primary sites include the colon, pancreas, and urachus. Historically, PMP was referred to as a “false mucinous tumor of the peritoneum,” reflecting early confusion about its origin.

Can PMP Spread?

Yes, PMP spreads extensively within the abdominal cavity, but it rarely metastasizes outside it. The disease primarily affects peritoneal surfaces and abdominal organs through progressive mucin accumulation rather than distant spread via blood or lymphatics.

Classification and Disease Severity

Low-Grade vs High-Grade PMP

Pseudomyxoma peritonei is broadly classified into low-grade and high-grade disease based on histopathology.

• Low-grade PMP (often associated with low-grade appendiceal mucinous neoplasms, LAMNs) is characterized by abundant mucin with relatively bland tumor cells and slower progression.
• High-grade PMP shows more aggressive cellular features, greater cellular abnormality, and an increased risk of recurrence and reduced survival.

Although PMP does not follow traditional organ-based cancer stages (I–IV) in the usual sense, disease staging focuses on tumor distribution within the peritoneal cavity and histologic grade. Modern staging systems emphasize tumor biology and disease burden rather than distant metastasis.

Growth Rate and Malignant Potential

The growth rate of PMP varies according to its histologic grade and may influence the rate of mucin accumulation and disease burden within the peritoneal cavity.

Although some forms appear indolent, PMP is not truly benign. Even low-grade disease can become life-threatening if untreated due to ongoing mucin production and organ compression. Therefore, PMP is considered a malignant condition with variable biological behavior.

Peritoneal Cancer Index (PCI)

The Peritoneal Cancer Index is the most widely used tool for assessing disease severity. It measures:

• The extent of tumor spread across 13 abdominal regions
• The size of tumor deposits in each region

The scoring scale ranges from 0 to 39, with higher values reflecting more extensive disease.

PCI is critical in treatment planning. Patients with lower PCI scores are more likely to achieve complete cytoreduction during surgery, which strongly correlates with improved survival. A very high PCI may limit surgical feasibility or affect prognosis.

Prognostic Factors

Several factors influence outcomes in PMP:

• Histologic grade (low vs high)
• Completeness of cytoreductive surgery (CC score)
• PCI score at diagnosis
• Tumor marker levels (CEA, CA19-9, CA-125)
• Molecular features (e.g., KRAS and GNAS mutations)

Low-grade disease treated with complete cytoreduction and HIPEC is associated with long-term survival in many patients.

Clinical Presentation and Symptoms

What Are the First Signs of Pseudomyxoma Peritonei?

Early symptoms are often subtle and nonspecific, which contributes to delayed diagnosis. The most common initial sign is gradual abdominal distension due to mucin accumulation.

Other common symptoms include:

• Abdominal pain or discomfort
• Bloating and increasing abdominal girth
• Early satiety (feeling full quickly)
• Nausea
• Unexplained weight gain
• Hernias (especially umbilical or inguinal)
• Bowel obstruction in advanced cases

In women, PMP may be discovered during evaluation for a presumed ovarian mass.

Pregnancy and Fertility

PMP can complicate pregnancy due to increased intra-abdominal pressure and tumor burden. In certain cases, it is unexpectedly diagnosed during a cesarean section. Fertility may be affected depending on disease extent and the need for cytoreductive surgery, which can involve the removal of reproductive organs. Fertility preservation counseling is therefore important in younger patients.

Diagnosis

Imaging: CT and MRI

Contrast-enhanced CT scan is the primary imaging modality. Typical findings include:

• Low-density mucinous ascites (build-up of thick, jelly-like fluid in the abdomen)
• Scalloping of the liver and spleen (indentation or compression of organ surfaces by mucin deposits)
• Omental “caking” (thickening of the fatty abdominal lining due to tumor deposits)
• Appendiceal mass (abnormal growth or swelling in the appendix)

MRI may better characterize mucin distribution and small peritoneal implants, particularly in surgical planning.

Blood Tests and Tumor Markers

Serum tumor markers are helpful in diagnosis and monitoring:

• CEA (carcinoembryonic antigen)
• CA-125
• CA19-9

Elevated levels may correlate with tumor burden and prognosis.

Biopsy and Histopathology

Diagnosis is confirmed through tissue sampling, which may be obtained via:

• Image-guided needle biopsy
• Diagnostic laparoscopy

Histopathologic examination determines tumor grade and guides staging and treatment planning.

Molecular Profiling

Genetic analysis frequently reveals mutations in:

• KRAS
• GNAS

These mutations are common in appendiceal mucinous tumors and support the diagnosis of PMP-related neoplasms.

Differential Diagnosis

Peritoneal Carcinomatosis vs PMP

Peritoneal carcinomatosis typically arises from gastrointestinal or ovarian cancers and spreads aggressively, often with solid tumor nodules rather than abundant mucin.

PMP vs Appendiceal Cancer

PMP is usually caused by appendiceal tumors but represents a clinical syndrome of peritoneal spread. Not all appendiceal cancers result in PMP.

PMP vs LAMN

LAMN is the primary appendiceal tumor. PMP occurs when LAMN ruptures and disseminates mucin-producing cells into the peritoneum.

PMP vs Goblet Cell Adenocarcinoma

Goblet cell adenocarcinoma is a distinct, more aggressive appendiceal tumor with mixed neuroendocrine features and different treatment considerations.

PMP vs Ascites

Simple ascites is free fluid accumulation due to liver disease or other causes. PMP involves thick, mucinous material with tumor cells, not just fluid.

PMP Treatment Approaches

Cytoreductive Surgery (CRS)

The primary objective of cytoreductive surgery is complete macroscopic tumor removal, meaning all visible disease and mucin deposits are surgically excised. Since PMP spreads throughout the peritoneal cavity rather than forming a single mass, surgery is often extensive and carefully planned.

What Happens During CRS?

CRS involves removing tumor implants from affected peritoneal surfaces and involved organs. Common procedures include:

• Peritonectomy – stripping diseased peritoneal lining
• Omentectomy – removal of the omentum (often heavily involved)
• Bowel resections – removing affected segments of the small or large intestine
• Organ-specific resections, when necessary, such as:
  • Splenectomy
  • Partial gastrectomy
  • Hysterectomy and oophorectomy
  • Cholecystectomy
  • Resection of liver capsule deposits

The surgery is complex and may last 6–12 hours or longer, depending on disease burden.

Completeness of Cytoreduction (CC Score)

Surgical success is measured using the Completeness of Cytoreduction (CC) score:

• CC-0: No visible disease remains
• CC-1: Residual nodules <2.5 mm
• CC-2/3: Larger residual disease

Achieving CC-0 or CC-1 is strongly associated with improved survival.

Two-Stage Cytoreductive Surgery

In selected patients with extensive disease or high PCI scores, two-stage cytoreductive surgery may be considered. This approach divides the operation into two planned procedures, allowing recovery between stages and reducing operative risk. It may be used when complete resection in a single procedure would be unsafe due to tumor burden or patient condition.

What Is HIPEC and How Does It Work?

Hyperthermic Intraperitoneal Chemotherapy (HIPEC) is a treatment delivered immediately after CRS. Heated chemotherapy is circulated within the abdominal cavity for 60–90 minutes to eliminate microscopic residual tumor cells.

Why Heat Enhances Effectiveness

Heat (typically 41–43°C):

• Increases penetration of chemotherapy into tissues
• Enhances cytotoxic effects
• Improves drug uptake by tumor cells

This localized approach allows high drug concentration with limited systemic toxicity.

Common Chemotherapy Agents

Commonly used agents in HIPEC include:

• Mitomycin C
• Oxaliplatin
• Cisplatin (in selected cases)

Choice depends on tumor biology and institutional protocol.

When Is HIPEC Effective?

HIPEC is most effective when:

• Complete or near-complete cytoreduction (CC-0/1) is achieved
• Disease is confined to the peritoneal cavity
• Tumor biology is low- or intermediate-grade
• Performed immediately following CRS during the same surgical session

CRS + HIPEC: The Gold Standard Treatment

Why Combined Treatment Is Superior

CRS removes visible tumor deposits, while HIPEC targets microscopic residual disease. Together, they address both macroscopic and microscopic spread, which is essential in PMP due to diffuse peritoneal involvement.

Multiple studies demonstrate that CRS combined with HIPEC significantly improves overall survival and reduces recurrence compared to surgery alone or systemic therapy.

Patient Selection Criteria

Not all patients are candidates for CRS + HIPEC. Selection depends on:

• Disease burden (PCI score)
• Tumor grade (low vs high)
• Ability to achieve complete cytoreduction
• Overall health and fitness for major surgery

Careful preoperative evaluation is essential.

Alternative and Adjunctive Treatment Approaches

Early-Stage or Limited Disease

In rare cases of very limited disease, early surgical intervention may prevent progression. However, observation alone is generally not recommended once PMP is confirmed.

Systemic (Intravenous) Chemotherapy

Systemic chemotherapy may be used:

• In high-grade PMP
• When the disease is unresectable
• As palliative treatment

However, its effectiveness is limited in PMP due to poor penetration into mucinous deposits.

Repeat CRS + HIPEC

For selected patients with localized recurrence and good performance status, repeat CRS + HIPEC may be considered. Outcomes depend on disease extent and interval since prior treatment.

Palliative Approaches for Advanced Disease

When curative surgery is not feasible, symptom-focused strategies are used:

Debulking Surgery

Removes large mucin volumes to relieve symptoms such as bowel obstruction and abdominal pressure, but does not aim for complete cytoreduction.

PIPAC (Pressurized Intraperitoneal Aerosol Chemotherapy)

An innovative, minimally invasive technique that delivers aerosolized chemotherapy laparoscopically under pressure. It may be considered for unresectable disease to control tumor progression and symptoms. However, PIPAC's role in PMP remains largely investigational, and it is not yet established as standard therapy.

Recovery, Risks, and Long-Term Outcomes

Hospital Stay and Recovery Timeline

CRS + HIPEC is a major abdominal surgery, and recovery requires time and structured follow-up. The typical hospital stay ranges from 10 to 21 days, depending on the extent of surgery and postoperative progress. Initial recovery in the intensive care or high-dependency unit may be required for close monitoring.

Full physical recovery can take 2–3 months, with a gradual return to normal activities. Fatigue is common in the early weeks, and nutritional rehabilitation plays a central role in recovery.

Potential Complications and Side Effects

As CRS involves extensive peritoneal and organ resections, complications may occur. These can include:

• Infections (wound, intra-abdominal, or systemic)
• Bowel dysfunction, including delayed return of bowel activity or obstruction
• Anastomotic leak (leakage from a surgical connection between two hollow organs, usually after bowel or gastric surgery; rare but serious)
• Nutritional challenges, particularly if multiple bowel segments are removed
• Fluid imbalances or electrolyte disturbances

Postoperative morbidity varies by center and disease burden, but outcomes are significantly better in experienced institutions.

Is a Stoma Required?

Extensive bowel resection or increased healing risk may necessitate the creation of a temporary or permanent stoma (colostomy or ileostomy). In many cases, stomas are temporary and reversed after recovery. The need depends on tumor location, surgical findings, and patient safety considerations. Not all patients require one.

Life Expectancy and Survival

Pseudomyxoma peritonei is not automatically terminal, especially when treated with CRS + HIPEC. Prognosis depends largely on tumor grade and completeness of cytoreduction.

• Low-grade PMP treated with complete CRS + HIPEC often has 5-year survival rates ranging between 60–80% in specialized centers.
• Some patients live 10–20 years or longer following treatment.
• High-grade disease carries a more guarded prognosis.

Risk of Recurrence

Recurrence can occur, particularly in high-grade disease or when complete cytoreduction is not achieved. Reported recurrence rates after CRS + HIPEC vary across studies. For example, disease progression was observed in 111 of 402 patients (28%) in one large series, while another multicenter database analysis reported 229 recurrences among 948 patients (24.2%) treated with curative intent. However, selected patients may undergo repeat CRS + HIPEC, which can extend survival in appropriate cases.

Quality of Life After CRS + HIPEC

Although recovery is demanding, many patients report good long-term quality of life once fully recovered. Abdominal distension, pain, and obstructive symptoms often improve significantly after successful cytoreduction. Physical strength and nutritional status typically improve over months.

Long-Term Monitoring and Surveillance

Follow-up is essential and generally includes:

• Regular physical examinations
• Periodic CT imaging
• Monitoring tumor markers (CEA, CA19-9, CA-125)

Surveillance intervals are typically every 3–6 months initially, then annually, depending on stability and risk profile.

Advances and Emerging Strategies in PMP Treatment

Research into PMP continues to evolve, focusing on improving survival while reducing morbidity.

Immunotoxin Therapy

Investigational approaches include immunotoxin therapy, which targets tumor cells using antibody-linked toxins designed to selectively destroy malignant cells while sparing normal tissue.

Bromelain-Based Intraperitoneal Therapy

Studies have explored bromelain-based intraperitoneal injections, aimed at breaking down mucin and improving drug penetration. These approaches remain investigational but may enhance treatment in mucin-dense disease.

Cancer Vaccines and Clinical Trials

Therapeutic vaccines targeting tumor-specific molecular pathways are under investigation. Taking part in clinical trials may allow access to investigational treatments for advanced or recurrent PMP.

Refinements in Surgical Techniques

Modern surgical advances include:

• Better PCI assessment
• Two-stage CRS in selected high-burden cases
• Improved perioperative care protocols
• Enhanced recovery pathways (ERAS)

These refinements have improved safety and outcomes.

Molecular Profiling and Precision Oncology

Molecular profiling has identified common mutations such as KRAS and GNAS, opening avenues for targeted therapies. While most targeted treatments remain investigational, precision oncology approaches are being explored to personalize systemic therapy in selected patients.

Choosing the Right Treatment Center

Importance of High-Volume HIPEC Centers

CRS + HIPEC is complex, and outcomes are strongly linked to institutional experience. High-volume centers demonstrate:

• Lower complication rates
• Higher rates of complete cytoreduction
• Improved long-term survival

Multidisciplinary Team Approach

Optimal care requires collaboration among:

• Surgical oncologists
• Medical oncologists
• Radiologists
• Pathologists
• Specialized nursing and nutrition teams

This coordinated approach ensures appropriate staging, treatment planning, and follow-up.

Experience matters. Surgeons trained in peritoneal surface malignancies and institutions equipped for complex oncologic surgery provide the safest and most effective care. When possible, referral to specialized centers with established HIPEC programs is strongly recommended.

 

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