Pseudomyxoma Peritonei (PMP) is a rare but critical clinical condition characterized by the progressive accumulation of mucinous ascites within the peritoneal cavity, often originating from a mucin-producing neoplasm, most commonly of the appendix. Known as “jelly belly,” PMP leads to significant morbidity and, if left untreated, mortality due to complications such as bowel obstruction and cachexia. 

Despite its rarity, PMP presents a diagnostic and therapeutic challenge due to its insidious onset, nonspecific symptoms, and complex management, which often requires cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) for optimal outcomes. 

This article explores Pseudomyxoma Peritonei in detail, covering definitions, classifications, causes, pathophysiology, clinical manifestations, diagnostic approaches, management strategies, complications, prognosis, and prevention strategies. 

Pseudomyxoma Peritonei is a condition characterized by the accumulation of mucinous material in the peritoneal cavity, usually arising from a perforated mucinous neoplasm. The disease progresses slowly but continuously, causing morbidity from the compressive effects of mucinous ascites on intra-abdominal organs. 

Definitions: 

• PMP: The presence of mucinous ascites in the peritoneal cavity due to intraperitoneal spread of mucin-producing neoplastic cells. 

• Disseminated Peritoneal Adenomucinosis (DPAM): Subtype with abundant mucin and scant low-grade epithelial cells; associated with better outcomes. 

• Peritoneal Mucinous Carcinomatosis (PMCA): Subtype with mucin pools containing more malignant cells; associated with poorer prognosis. 

Key Points: 

• PMP is a clinicopathologic syndrome arising from mucin-producing tumors, most commonly of appendiceal origin. 

• The hallmark is copious intraperitoneal mucin accumulation. 

Epidemiology of PMP 

• PMP incidence: ~1–2 cases per million annually. 

• More common in adults, slight female predominance. 

• Peak presentation: fifth to sixth decade of life. 

• Appendiceal tumors cause ~90% of cases. 

• Female predominance is partly due to incidental detection during gynecologic procedures. 

Understanding the causes of PMP is important for recognizing how this disease originates and why it progresses in the way it does. While most cases are linked to appendiceal tumors, other mucin-producing organs may also be involved. The following outlines the primary sites of origin, underlying mechanisms, and risk factors. 

Primary Sites of Origin: 

1. Appendiceal Mucinous Tumors (most common): 

• Low-grade appendiceal mucinous neoplasms (LAMNs) 

• Mucinous adenocarcinomas 

2. Ovarian Mucinous Tumors: 

• Usually secondary involvement from an appendiceal primary. 

3. Other rare origins: Colon, pancreas, urinary bladder, gallbladder. 

Pathogenesis: 

• Tumor rupture releases neoplastic cells into the peritoneal cavity. 

• These cells continue producing mucin, leading to progressive ascites. 

Risk Factors: 

• Appendiceal mucinous tumors 

• Ovarian mucinous tumors 

• History of appendiceal rupture 

• Rare familial genetic predispositions 

The key mechanism: 

• Perforation or leakage of a mucinous tumor seeds the peritoneal cavity with mucin-producing cells. 

• Cells implant on peritoneal surfaces (omentum, paracolic gutters, diaphragm, pelvis). 

• The “redistribution phenomenon” explains why mucin accumulates in areas of fluid resorption. 

• Continuous mucin production compresses bowel loops, causing obstruction, reduced mobility, and malnutrition. 

Histopathological Classification (Ronnett et al.): 

1. DPAM: Low cellularity, abundant mucin, low-grade epithelium. 

2. PMCA: Higher cellularity, malignant epithelial cells, invasive features. 
3. Intermediate/Hybrid: Mixed features. 

Because PMP develops slowly, its symptoms often progress subtly and may be mistaken for other abdominal or gastrointestinal conditions. Early manifestations can be vague, which delays diagnosis until the disease has advanced. Over time, as mucin continues to accumulate, patients begin to notice changes that reflect the increasing pressure and displacement of abdominal organs. 

Healthcare providers should be alert to the following symptoms and signs: 

Common Symptoms: 

• Increasing abdominal girth 

• Abdominal pain or discomfort 

• Weight loss 

• Early satiety 

• Bowel habit changes (constipation, intermittent obstruction) 

• Nausea and vomiting 

Physical Findings: 

• Distended, tense abdomen 

• Palpable mucinous deposits 

• Fluid thrill in advanced ascites 

• Hernias (umbilical or inguinal) 

PMP is sometimes discovered incidentally during surgery for appendicitis, ovarian masses, or hernia repair. 

Clinical Evaluation: 

Clinical evaluation begins with a careful history, often noting a background of an appendiceal or ovarian mass, previous appendectomy, or progressive abdominal enlargement. Physicians also perform a detailed physical examination, which may suggest the presence of ascites or reveal palpable intra-abdominal masses. Together, these findings guide further imaging and diagnostic work-up. 

• History of appendiceal/ovarian mass, appendectomy, or increasing abdominal girth. 

• Physical exam suggesting ascites or palpable masses. 

Imaging: 

• Ultrasound: Echogenic, loculated ascites; non-mobile septations. 

• CT Scan (preferred): Liver/spleen “scalloping,” low-attenuation gelatinous ascites, peritoneal implants, possible primary mass. 

• MRI: Hyperintense mucin collections on T2-weighted imaging. 

Tumor Markers: 

• CEA, CA 19-9, CA-125 (useful for monitoring but not diagnostic). 

Diagnostic Laparoscopy: 

• Direct visualization and biopsy confirm disease and extent. 

Differential Diagnosis 

Differential diagnosis refers to the process of distinguishing PMP from other conditions that present with similar abdominal findings. This step is essential to ensure accurate diagnosis and guide proper management. 

Conditions resembling PMP: 

• Malignant peritoneal carcinomatosis (non-mucinous) 

• Tuberculous peritonitis 

• Peritoneal mesothelioma 

• Cirrhotic ascites 

• Ovarian carcinoma 

• Peritoneal sarcomatosis 

Staging and Classification of PMP 

Staging and classification are necessary to determine the extent of disease, predict prognosis, and guide treatment planning. They allow clinicians to compare outcomes across studies and select the most appropriate management strategies for each patient. 

• Peritoneal Cancer Index (PCI): Scores 13 regions of the abdomen based on lesion size; guides surgical planning. 

• Histopathology: DPAM vs. PMCA vs. Hybrid. 

• AJCC Staging (8th edition): Integrates primary tumor stage with peritoneal spread. 

The management of PMP is complex and often requires specialized surgical oncology expertise. Treatment is usually multimodal, combining surgery and intraperitoneal chemotherapy to control disease spread and improve survival. The following approaches outline the main strategies currently used: 

1. Cytoreductive Surgery (CRS): 

• Removal of visible peritoneal disease: peritonectomy, omentectomy, splenectomy, bowel resections, removal of ovaries (if involved). 

• Aim: complete cytoreduction (CC-0 or CC-1). 

2. Hyperthermic Intraperitoneal Chemotherapy (HIPEC): 

• Heated chemotherapy (41–43°C) circulated in peritoneal cavity after CRS. 

• Common drugs: mitomycin C, oxaliplatin. 

• Targets microscopic residual disease. 

3. Perioperative Systemic Chemotherapy: 

• Limited role; reserved for high-grade PMCA, unresectable, or recurrent disease. 

4. Palliative Care: 

• For unresectable/advanced cases: paracentesis, bowel decompression, nutritional support. 

Prognostic Factors: 

• Histopathological subtype (DPAM vs. PMCA) 

• Completeness of cytoreduction (CC score) 

• Tumor burden (PCI) 

• Preoperative tumor marker levels 

Survival: 

• CRS + HIPEC for low-grade PMP (DPAM): 5-year survival 70–90%. 

• High-grade PMP (PMCA): 5-year survival 20–50%. 

• Incomplete cytoreduction worsens prognosis. 

Complications from PMP can arise both from the disease itself and from the treatments used to manage it. These issues often contribute significantly to patient morbidity and must be anticipated and monitored carefully throughout care. 

Disease-Related: 

• Bowel obstruction 

• Malnutrition and cachexia 

• Hernias from increased intra-abdominal pressure 

• Respiratory compromise 

Treatment-Related: 

• Surgical complications: bleeding, infection, leaks 

• HIPEC complications: renal toxicity, marrow suppression, electrolyte imbalance 

• Postoperative ileus, adhesions 

Prevention of PMP largely focuses on early recognition and careful management of precursor lesions, since primary prevention is not possible. Timely diagnosis of appendiceal mucinous tumors before rupture, thorough evaluation of ovarian mucinous tumors, and awareness of PMP in patients with unexplained mucinous ascites are all essential in reducing progression and improving outcomes. 

Lifelong follow-up is essential for patients with PMP. This involves regular physical examinations along with monitoring tumor markers such as CEA, CA 19-9, and CA-125. Periodic CT scans are also recommended to detect recurrence at an early stage. Identifying relapse promptly allows for the possibility of secondary cytoreduction, which can improve outcomes and prolong survival. 

Pseudomyxoma Peritonei is a rare but serious condition defined by progressive mucinous ascites that, if untreated, leads to morbidity and mortality. Early diagnosis and treatment with CRS and HIPEC remain the standard of care, significantly improving survival in well-selected patients. 

A multidisciplinary approach—including surgeons, oncologists, radiologists, pathologists, and specialized nursing—is critical. Because recurrence is common, lifelong follow-up is mandatory. Ongoing research into molecular biology and targeted therapies offers hope for further improving outcomes. 

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3. Sugarbaker PH. Pseudomyxoma peritonei: a cancer whose biology is characterized by a redistribution phenomenon. Ann Surg. 1994;219(2):109-111. 

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