Pseudomyxoma of the peritoneum: what is it, symptoms, treatment, prognosis

What is a pseudomyxoma of the peritoneum?

Pseudomyxoma of the peritoneum Is a rare malignancy characterized by the progressive accumulation of mucus-secreting (mucinous) tumor cells in the abdominal cavity and pelvis. The disease develops after a small growth (polyp) located inside the appendix breaks through the wall of the appendix and spreads mucus-producing tumor cells to surrounding surfaces (for example, the membrane lining the abdomen [peritoneum]).

As mucinous tumor cells accumulate, the abdomen swells and digestive (gastrointestinal) function is impaired. Peritoneal pseudomyxoma develops at a variable rate, but may grow more slowly (sluggish) than other peritoneal malignancies.

Signs and symptoms

The most common symptoms in people with pseudomyxoma of the peritoneum are due to a progressive increase in mucinous tumor in the abdomen and pelvis. Usually, the most common symptoms are an enlarged abdomen (called a "gelatinous belly") and abdominal discomfort from pressure. Although the abdomen may be distended, touching it (palpation) is usually painless. In affected men, the second most common symptom is protrusion of parts of the intestines through an abnormal opening in the muscular wall of the abdomen near the groin (

inguinal hernia). In affected women, the second most common symptom is usually an abnormal enlargement of the ovary. The mucinous tumor grows rapidly in the ovarian tissue.

A mucinous tumor accumulates in the fatty membrane in front of the intestine (greater omentum), under the muscles that separate the chest from the abdomen (diaphragm), and inside the pelvis. In most cases, the small intestine is not affected. Often, the primary tumor that ruptures the appendix may be small compared to the extensive mucinous tumor developing in the abdomen and pelvis. Without proper treatment, the disease will lead to intestinal obstruction or loss of bowel function. The progressive accumulation of mucinous tumors can lead to malnutrition, malnutrition and ultimately life-threatening complications.

Causes

As with the vast majority of tumors, the exact cause of peritoneal pseudomyxoma is unknown. It is known that genetic, familial or environmental factors cannot cause this disease.

A peritoneal pseudomyxoma develops from a hole (perforation) in the appendix caused by the penetration of a small growth (polyp) located inside the appendix. Tumor cells from the appendix spread (migrate) in the abdomen and pelvis to characteristic sites. Once they reach these sites, the tumor cells continue to grow. The characteristic sites for the growth of tumor cells are inside the fatty membrane in front of the intestine. (greater omentum), under the muscles that separate the chest from the abdomen (diaphragm), and inside pelvis. Women may have overgrowth in both ovaries.

Affected populations

Pseudomyxoma of the peritoneum is a very rare disease, about 2 cases per million people. Men and women suffer equally. It is a misconception that women develop the disease more often than men. However, this misconception arises from the fact that some ovarian tumors are often mistakenly identified as pseudomyxoma of the ovaries.

The average age of onset of pseudomyxoma of the peritoneum is 48 years, which is much earlier than in other malignant neoplasms of the abdominal cavity.

Symptomatic disorders

Symptoms of the following diseases may be similar to those of pseudomyxoma of the peritoneal cavity. Comparisons can be useful for differential diagnosis:

• Malignant neoplasm of the ovariesknown as ovarian cancer with low potential for malignancy, may resemble a pseudomyxoma of the peritoneum. However, this tumor remains a single, increasing mass of the ovaries. It is not distributed over the abdominal cavity and must be distinguished from a pseudomyxoma of the peritoneum. Symptoms may include abdominal or lower back pain. The exact cause of low ovarian cancer is unknown.
• Mucinous cancer ovaries, colon, stomach and gallbladder can cause excess mucus in the peritoneum. These cancers are usually much more aggressive than mucinous tumors of the appendix. They lead to rapidly progressive accumulation of mucus in the peritoneum and intestinal obstruction. The exact cause of these tumors is unknown.
• Adenocarcinoid (goblet carcinoid) of the appendix is ​​similar to the pseudomyxoma of the peritoneum. A mucinous tumor from adenocarcinoid spreads through the abdominal cavity like a pseudomyxome of the peritoneum. However, this tumor is much more aggressive than the tumor with pseudomyxoma of the peritoneum. The symptoms of this type of cancer often resemble those of acute appendicitis. The exact cause of appendix adenocarcinoid is unknown.
• Mesothelioma Is a rare form of cancer that affects the membrane that covers and protects various internal organs of the body (peritoneum). The mesothelium is made up of two layers of specialized cells known as mesothelial cells. One layer directly surrounds all intra-abdominal organs (visceral peritoneum); the other forms a protective sac surrounding the entire abdominal cavity and pelvis (parietal peritoneum). The most common form of mesothelioma affects the membrane or sac that lines the lungs (pleura). Other common sites include the membrane lining the stomach, small and large intestine (peritoneum), and the membrane lining the heart (pericardium). Mesotheliomas can lead to the accumulation of a mucinous tumor in the abdominal cavity, which is very difficult to distinguish from a pseudomyxoma of the peritoneum. The symptoms of mesothelioma differ depending on the location, type and stage of the cancer. Roughly 80 percent of mesothelioma cases result from exposure to asbestos. Symptoms of mesothelioma may not appear until 50 years after the initial exposure to asbestos. However, once symptoms become apparent, mesothelioma can progress rapidly and cause life-threatening complications.
• Appendicitis- acute inflammation of the appendix. It is characterized by abdominal pain and inflammation of the abdominal mucosa. The first sign of appendicitis is unusual mild discomfort in the navel area. The pain usually becomes more intense and localized in the lower right abdomen. Other symptoms of appendicitis include fever, loss of appetite, vomiting and abdominal soreness.

Diagnostics

The diagnosis of pseudomyxoma of the peritoneum can be confirmed by radiologic techniques such as computed tomography or MRI of the abdomen (magnetic resonance imaging). These imaging tests can reveal a characteristic distribution of large amounts of mucus in specific areas of the abdomen and pelvis. They can also localize the primary tumor in an area of ​​the appendix called a mucocele.

Standard treatments

The goal of treating pseudomyxoma of the peritoneum is a complete cure for the disease. This is achieved in about 65% of patients. Treatment is cytoreductive surgery with peritonectomy to remove all visible signs of disease from the abdomen and pelvis. Because the mucinous tumor is so widespread in the abdomen and pelvis, the operation can take up to 12 hours. Then, to prevent re-implantation of cancer cells, the abdomen is rinsed with warm chemotherapy solution. This is commonly referred to as hyperthermic intraperitoneal chemotherapy or HIPEC.

Sometimes the surgeon must look carefully for the primary appendix tumor, as it can be very small in size. compared with mucinous tumor and mucinous ascites, which can accumulate in kilograms in the abdominal cavity and the pelvis.

Hyperthermic intraperitoneal drugs that are commonly used to treat the disease include mitomycin C and oxaliplatin. Chemotherapy is heated to 42 degrees in the abdomen to increase drug penetration into the mucinous tumor and increase local cytotoxicity.

Prognosis and complications

The average operation time is 6 to 12.6 hours, and with such complex procedures, morbidity and mortality are significant. Major diseases include anastomotic leakage, intestinal and pancreatic fistulas, pneumonia, thromboembolism and intra-abdominal abscesses. Many patients had previously undergone abdominal surgery prior to final cytoreduction, which increased the risk of complications associated with with adhesiolysis and disruption of anatomy, which leads to a high incidence of fistulas of the small intestine and significant blood loss.

Neutropenic sepsis - a potentially serious complication, usually manifested around the 10th day after intraperitoneal injection of mitomycin C due to bone marrow toxicity. Septic complications can be a harbinger or result neutropenia and require surgical treatment.

The reoperation rate for postoperative complications ranges from 11% to 21%, and the mortality rate ranges from 0% to 14%. The average hospital stay ranges from 16 to 21 days.

Lilia Khabibulina/ article author