This is a very common question. The term “cancer” refers to malignant tumors, which behave very differently from benign tumors, the latter being more easily treatable. Pseudomyxoma peritonei is a rare condition that often causes confusion among patients and even some healthcare professionals.
Pseudomyxoma peritonei, which refers to the accumulation of mucin (a jelly-like substance) in the abdomen, typically originates from a tumor in the appendix. Mucin is a gelatinous substance that can spread throughout the abdominal cavity, leading to the formation of masses and abdominal distension. Most of these tumors are benign and are classified as “low-grade mucinous neoplasms” or “high-grade mucinous neoplasms,” depending on the cellular characteristics observed under the microscope.
Despite being benign, these tumors can spread throughout the abdomen and cause pseudomyxoma. The spread occurs due to the rupture of the initial tumor, releasing mucin into the abdominal cavity. This mucin can adhere to various surfaces within the abdomen, such as the peritoneum, which is the membrane lining the abdominal cavity and covering the organs within it.
Also, read: Is pseudomyxoma a common disease?
Despite sounding unusual, most pseudomyxomas are not cancer but rather a unique dissemination of a benign type of tumor from the appendix. This condition, though benign, can be quite serious because mucin can lead to complications such as intestinal obstructions and respiratory difficulties due to abdominal swelling. Treatment involves surgically removing the mucin and affected tissue, followed by intraperitoneal chemotherapy to eliminate any remaining tumor cells.
Of course, there are exceptions. About 20% of pseudomyxoma cases are caused by adenocarcinomas of the appendix, which are malignant tumors—a form of cancer. Adenocarcinomas are tumors that can invade nearby tissues and spread to other parts of the body (metastasis). Nevertheless, despite their relative severity, the disease is still managed as pseudomyxoma, and with early diagnosis and appropriate treatment, there is a high chance of cure.
Pseudomyxoma peritonei is an extremely rare disease, with an estimated annual incidence of 1 in 1,000,000, meaning that in a single year, only one person out of one million will have pseudomyxoma. To put this into perspective, common conditions like colorectal cancer and gallstones (cholelithiasis) affect approximately 1 in 22 and 1 in 10 individuals over their lifetime, respectively.
Pseudomyxoma peritonei is characterized by the presence of mucinous ascites or implants in the peritoneal cavity. It usually originates from lesions in the appendix or ovaries. The disease is typically diagnosed after the age of 40. In 30 to 50% of cases, patients experience progressive abdominal distension, often mistaken for weight gain.
Diagnosing pseudomyxoma peritonei can be challenging as the symptoms are often subtle and nonspecific. In addition to abdominal distension, less common symptoms include abdominal pain, weight loss, urinary symptoms, constipation, vomiting, and shortness of breath. Diagnosis may follow the discovery of an ovarian mass in women or the recent development of inguinal hernia, appendicitis, or intestinal obstruction.
The most commonly used diagnostic procedures for diagnosing and staging pseudomyxoma peritonei include chest, abdomen, and pelvic computed tomography (CT), abdominal puncture, diagnostic laparoscopy, and laboratory tests. CT scans can provide images of the initial lesion of affected tissue, as well as signs of mucin in the abdominal cavity.
With advancements in medical technology and greater availability of imaging tests, it is not uncommon for pseudomyxoma peritonei to be incidentally discovered. For example, a person may undergo an MRI to investigate back pain or a CT scan ordered by a urologist to investigate a kidney stone. In such cases, the scans may reveal signs of pseudomyxoma peritonei, even though this was not initially suspected.
Read also: Is pseudomyxoma considered cancer?
Imaging tests such as computed tomography (CT) and magnetic resonance imaging (MRI) are valuable tools for diagnosing pseudomyxoma peritonei. They can provide images of the initial lesion of affected tissue, as well as signs of mucin in the abdominal cavity. These exams allow for a better assessment of lesions due to their spatial resolution capabilities, multiplanar images, and different sequences (in MRI).
In summary, pseudomyxoma peritonei is a rare disease, and its diagnosis is often challenging due to its nonspecific clinical presentation. Compared to more common conditions like colorectal cancer and gallstones, the rarity of pseudomyxoma peritonei is notable. However, with awareness and early diagnosis, patients have the opportunity to receive appropriate treatment and improve their quality of life. Routinely undergoing imaging tests for other conditions can facilitate the discovery of pseudomyxoma peritonei, underscoring the importance of regular health check-ups.
Pseudomyxoma peritonei is a rare and complex condition that requires careful selection of the treatment method to ensure the best possible chance of cure. In this context, the laparoscopic approach (via video) has emerged as a promising technique that can be employed in very specific situations.
Although appealing as an option, it is important for patients to know that this technique is applicable in only a minority of cases, about 5% of them. It can be applied in patients whose pseudomyxoma is low-grade (low aggressiveness) and has a low Peritoneal Carcinomatosis Index (PCI). The PCI is a measure that assesses the extent of cancer spread in the peritoneum. The lower the PCI, the greater the chance of complete cytoreduction, meaning the total surgical removal of the tumor.
The laparoscopic procedure stands out for its advantages, including greater comfort in the postoperative period, faster recovery, and a lower risk of complications compared to open surgery. However, the technique requires a team with advanced laparoscopic skills and familiarity with this rare disease. In very exceptional and selected cases, the laparoscopic approach may then be combined with HIPEC.
Again, it is important to emphasize that the laparoscopic approach with HIPEC is restricted to a small subset of patients. For more advanced cases of pseudomyxoma, with high PCI and high-grade tumors, open surgery, or laparotomy, remains the international standard of treatment.
Laparotomy allows for comprehensive exploration of the abdominal cavity, facilitating the complete removal of tumors. Although it is a more invasive operation, open surgery offers a better chance of effective disease control in more complex cases.
The decision between the laparoscopic approach and open surgery depends on a careful analysis of the patient’s clinical picture, considering tumor characteristics, disease extent, and the experience of the medical team.
If you or someone you know has been diagnosed with pseudomyxoma peritonei or has questions about treatment options, please do not hesitate to contact us. Our specialized medical team is ready to provide guidance and detailed information to ensure the best approach for your case.
Historically, peritoneal pseudomyxoma has always been discovered in very advanced stages of the disease. The mucin (gelatin) produced by the tumor accumulates over many months, sometimes years. The impression a person has is that they are gaining weight, and it is not uncommon for them to try some type of diet—obviously without success.
Also read: Is pseudomyxoma considered cancer?
The patient seeks a doctor when the volume of the abdomen is large and difficulties in breathing and eating arise, along with diffuse and constant pain.
This overall picture has changed a lot in recent years, especially in the last ten years. Today, the use of imaging exams is more widespread. It is normal for people to undergo an abdominal ultrasound every year (especially women), or even more sophisticated tests like CT scans or MRIs.
In our experience, we have had patients who discovered pseudomyxoma after having an MRI to investigate back pain, or after a CT scan requested by a urologist to investigate a kidney stone.
When the disease is discovered this way, through exams requested for another reason, the tendency is to make the diagnosis at a much earlier stage of the disease, facilitating treatment.
One last situation worth mentioning is that of patients who discover pseudomyxoma after being operated on for suspected appendicitis, that infection of the appendix that needs to be treated with emergency surgery. During the procedure, the surgeon ends up discovering the mucin inside the abdominal cavity.
If you have diagnosed peritoneal pseudomyxoma in one of the last two situations described, exams requested for another cause or surgery for suspected appendicitis, know that there is an excellent possibility that a relatively early diagnosis has been made, and the chances of success in treatment are great.
Discovered peritoneal pseudomyxoma and looking for the best place for treatment? Find specialized centers that offer early diagnosis and effective treatment now.
por
Pseudomixoma Peritoneal © 2026
