Introduction
Pseudomyxoma peritonei is characterized by the accumulation of jelly-like fluid in the abdominal cavity. This condition may involve fluid buildup, the formation of lumps on the lining of the abdomen known as peritoneal nodules, and the potential involvement of organs such as the ovaries. PMP typically originates from the appendix. Accurate diagnosis aided by imaging is crucial, as is determining its stage, which guides treatment. Treatment options encompass surgical debulking, hyperthermic intraperitoneal chemotherapy (HIPEC), and chemotherapy alone or in combination.
What Is Pseudomyxoma Peritonei?
It is a rare medical condition characterized by the abnormal accumulation of gel-like fluid, known as mucinous ascites, within the peritoneal surfaces or abdominal cavity. It is colloquially referred to as "jelly belly." This condition originates from mucous-producing tumors that develop on abdominal structures, originating from the appendix and other organs like the pancreas, bowel, bladder, reproductive organs, and gall bladder. This condition progresses slowly and may be incidentally discovered during surgery or through a scan. It is considered a borderline malignancy. This condition predominantly affects females with an average age of 53.
What Is the Radiological Assessment for Pseudomyxoma Peritonei?
The radiological assessment involves imaging techniques, such as ultrasound, computed tomography (CT) scans, and magnetic resonance imaging (MRI). This assessment can help determine the location, extent, and severity, guiding the treatment decisions. Pseudomyxoma peritonei is usually characterized by a localized collection of fluids along the peritoneal surfaces (abdominal cavity), resulting in abdominal organs coated with a scalloped appearance, along with omental caking. Omental caking refers to infiltrating soft tissue into the omental fat, resulting in a thickened, swollen, or cake-like appearance. An appendiceal mucocele (an enlarged appendix containing mucus) is also present.
Since these tumors originate from the appendix and early spread is limited to the right lower side of the abdomen, deposits occur in the omentum, right diaphragm, near the intestines, and the pelvis (right side). This condition usually does not affect the small intestine in the early stages, but it can cause bowel destruction in later stages.
Features on Plain Radiographs Include:
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Signs of a buildup of fluids in the abdominal cavity result in the small intestine being pushed toward the center due to this fluid.
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Tiny calcifications can be seen, which appear as small dots or scattered curved lines.
Features of Ultrasound Include:
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Certain echogenic areas (bright areas) are seen within the abdominal region, indicating fluid buildup. These areas may also contain bright particles that do not move, while other particles, such as blood or pus, do.
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The loops of the small intestine are pushed toward the middle region of the abdomen.
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Furthermore, these images show an irregular or wavy pattern at the edges of organs such as the spleen or liver.
Features of CT Scans Include:
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The abdominal cavity can exhibit areas of low density (referred to as low-attenuation lesions), which indicate fluid-filled cavities that are not visible. These fluids can be observed throughout the abdominal cavity, such as in fatty tissues present over the intestines (called omentum) and in the mesenteric tissues that hold the intestines. These fluids are loculated, meaning they are confined to specific spaces.
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The edges of internal organs, such as the liver, appear irregular or wavy. This scalloping appearance is a result of fluid accumulation.
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There might be bright spots or curved lines that indicate calcification.
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This condition is often limited to the abdominal cavity, and involvement of the chest area is uncommon.
Features of MRI Include:
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When T1-weighted MRI sequences are used, the affected areas appear as dark signals, indicating low signals.
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When T2-weighted MRI sequences are used, the affected areas appear as brighter signals, thus indicating high signals.
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When a contrast agent such as gadolinium (Gd) is used during T1-weighted MRI sequences, the affected areas show enhanced brightness.
What Is the Management of Pseudomyxoma Peritonei?
The aggressiveness of the surgery is determined based on the Peritoneal Cancer Index (PCI), which aids in predicting the prognosis of the condition. This index can be calculated using CT and MRI scans. The management of pseudomyxoma peritonei includes:
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Complete Cytoreduction Surgery (CRS): This surgery involves the removal of all visible tumors, with no tumor larger than 0.0984 inches left behind.
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Hyperthermic Intraperitoneal Chemotherapy (HIPEC): HIPEC is a specialized treatment incorporating cytoreductive surgery to remove visible tumors as thoroughly as possible. Subsequently, a heated solution containing chemotherapy drugs is introduced into the peritoneal cavity. The temperature rises to 105.8 and 109.4 degrees Fahrenheit, enhancing drug penetration. This solution circulates within the peritoneal cavity for approximately one to two hours. Following treatment, the solution is drained, and incisions are sutured. This treatment has demonstrated improved outcomes. The most commonly utilized chemotherapeutic agent is Mitomycin C (MMC).
Patients undergoing CRS, along with HIPEC, experience better long-term outcomes. Major complications following this approach include:
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Thromboembolism: This is a condition in which blood clots form in the blood vessels, causing obstruction.
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Anastomotic Leak: This occurs when two sections of the digestive tract are joined together, and there is a leak at the connection site.
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Bowel Perforation: This refers to a tear in the wall of the bowel or intestine.
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Fistula Formation: This refers to an abnormal connection between two organs.
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Abscess: This is a collection of pus at the surgical site.
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Wound Dehiscence: This refers to the reopening of the surgical wound.
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Neutropenia: This is a decrease in the levels of neutrophils in the blood.
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Sepsis: It is a condition in which the body responds improperly due to an infection.
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Pleural Effusion: This refers to the accumulation of fluid around the lung spaces, which can result in breathing difficulties.
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Respiratory Insufficiency: This refers to decreased lung function, leading to breathing difficulties.
Conclusion
Radiological assessment plays a crucial role in the diagnosis, grading, treatment planning, and follow-up of pseudomyxoma peritonei. This disease requires a comprehensive approach integrating various imaging modalities, including computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound. Due to its rarity and complex nature, accurate imaging and precise interpretation are essential for appropriate interventions.
