The most common symptoms in individuals with pseudomyxoma peritonei occur due to progressively increasing mucinous tumor within the abdomen and pelvis. Usually, the most common symptom is increasing abdominal size (so called “jelly belly”) and abdominal pain. Although the abdomen may be swollen, it is generally not painful to touch (palpation). In affected males, the second most common finding 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 females, the second most common finding is usually an abnormally enlarged ovary. The mucinous tumor seems to grow rapidly within ovarian tissue.
The mucinous tumor accumulates within the fatty membrane in front of the intestines (greater omentum), beneath the muscle that separates the chest from the abdomen (diaphragm), and within the pelvis. In most cases, the small bowel is unaffected. Frequently, the primary tumor that punctured the appendix may be small in comparison to the extensive mucinous tumor that develops within the abdomen and pelvis. Without treatment intervention, this disorder will result in obstruction of the intestines or the loss of intestinal function. Progressive mucinous tumor accumulation can result in poor food intake, malnutrition, and, eventually, life-threatening complications.
The exact cause of pseudomyxoma peritonei is not known. There are no genetic, familial, or environmental factors known to cause this disorder.
Pseudomyxoma peritonei develops from a hole (perforation) in the appendix that is caused by the penetration of a small growth (polyp) located within the appendix. The tumor cells from the appendix spread (migrate) within the abdominal and pelvic cavity to characteristic locations. Once they reach these locations, tumor cells continue to grow. Characteristic locations for tumor cell growth are within the fatty membrane in front of the intestines (greater omentum), beneath the muscle that separates the chest from the abdomen (diaphragm), and within the pelvis. In females, there may be excessive growth on both ovaries.
Pseudomyxoma peritonei is a very rare disorder with approximately 2 cases per million individuals. Males and females are affected in equal numbers. It is a misconception that females develop this disorder more frequently than males. However, this misconception occurs because some ovarian tumors are frequently mistakenly identified as pseudomyxoma ovarii.
The average age of onset of pseudomyxoma peritonei is 48 years, which is considerably earlier than other malignancies that occur within the abdomen.
The diagnosis of pseudomyxoma peritonei may be confirmed by radiologic technologies such as abdominal CT scan or abdominal MRI (magnetic resonance imaging). These imaging tests may reveal the characteristic distribution of large amounts of mucus to particular locations within the abdomen and pelvis. They may also localize a primary tumor in the area of the appendix referred to as a mucocele.
The goal of the treatment of pseudomyxoma peritonei is cure. This is achieved in approximately 65% of patients. The treatments are cytoreductive surgery with peritonectomy in an attempt to remove all visible evidence of the disease from the abdomen and pelvis. Then, to prevent reimplantation of cancer cells, the abdomen is washed with a warm chemotherapy solution. This is commonly referred to hyperthermic intraperitoneal chemotherapy or HIPEC. Sometimes the surgeon must search carefully for the primary appendiceal tumor for it may be very small in comparison to the mucinous tumor and mucinous ascites that can accumulate in kilogram quantities within the abdomen and pelvis. The hyperthermic intraperitoneal drugs which are commonly used to treat this disease include mitomycin C and oxaliplatin. The chemotherapy is heated to 42 degrees in the abdominal cavity to increase penetration of the drugs into the mucinous tumor and to increase the local cytotoxicity.
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