Information on the following diseases can be found in the Related Disorders section of this report:

• Low Malignant Potential Ovarian Tumors
• Mucinous Cancers, General
• Adenocarcinoid (goblet cell carcinoid) of the Appendix
• Mesothelioma
• Appendicitis

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 500 cases discussed in the medical literature. 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.

Symptoms of the following disorders can be similar to those of pseudomyxoma peritonei. Comparisons may be useful for a differential diagnosis:

An ovarian malignancy known as low malignant potential ovarian tumor may look similar to pseudomyxoma peritonei. However, this tumor remains as a solitary, expanding ovarian mass. It does not distribute itself around the abdomen, and should be distinguishable from pseudomyxoma peritonei. Symptoms may include abdominal or lower back pain. The exact cause of low malignant potential ovarian tumor is not known.

Mucinous cancers of the ovary, colon, stomach, and gallbladder may produce an excess of mucous in the abdominal cavity. These cancers are much more aggressive than the mucinous tumor from the appendix. They result in rapidly progressing accumulation of mucous in the abdominal region and intestinal obstruction. The exact cause of these tumors is not known.

Adenocarcinoid (goblet cell carcinoid) of the appendix is similar to pseudomyxoma peritonei. The mucinous tumor from the adenocarcinoid distributes itself around the abdomen in a very similar fashion to pseudomyxoma peritonei. However, this tumor is much more aggressive than the tumor in pseudomyxoma peritonei. Symptoms of this type of cancer often resemble those of acute appendicitis. The exact cause of adenocarcinoid of the appendix is not known.

Mesothelioma is a rare form of cancer that affects the membrane that covers and protects various internal organs of the body (mesothelium). The mesothelium is composed of two layers of specialized cells known as mesothelial cells. One layer directly surrounds an organ; the other forms a protective sac around the organ. 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 (peritoneum) and the membrane lining the heart (pericardium). Mesotheliomas may result in a mucinous tumor accumulation within the abdomen that is very difficult to distinguish from pseudomyxoma peritonei. Symptoms of mesothelioma vary depending upon the location, type and stage of the cancer. Approximately 70 to 80 percent of cases of mesothelioma result from exposure to asbestos. Symptoms of mesothelioma may not appear until up to 50 years after initial exposure to asbestos. However, after symptoms began apparent, mesothelioma may rapidly progress to cause life-threatening complications. (For more information on this disorder, choose "mesothelioma" as your search term in the Rare Disease Database.)

Appendicitis is an acute inflammation of the appendix. It is characterized by abdominal pain and inflammation of the lining of the abdominal cavity (appendicitis). The first sign of this condition is an unusual slight discomfort around the navel. Pain typically becomes more intense and localize near the lower right-hand side of the abdomen. Other symptoms of appendicitis may include fever, loss of appetite, vomiting, and abdomen tenderness.

The diagnosis of Pseudomyxoma Peritonei may be confirmed by advanced imaging techniques such as ultrasound or CT scan. These imaging tests may reveal characteristic distribution of large amounts of mucus at particular locations within the abdomen and the pelvis.

The treatment of Pseudomyxoma Peritonei is directed toward the specific symptoms that are apparent in each individual. Surgery, such as incision of the peritoneum (peritonectomy), may be used to remove all visible tumor cells. The surgeon must search carefully for the primary appendix tumor, for it may be very small in comparison to the extensive tumor accumulation that is seen elsewhere within the abdomen and pelvis.

In order to prevent reaccumulation of mucinous tumor cells within the abdominal cavity (intraperitoneal), chemotherapy may be used along with surgery. Chemotherapy may be administered to individuals with Pseudomyxoma Peritonei. These drugs may include intraperitoneal mitomycin C and 5-fluorouracil.

Studies are ongoing in the treatment of Pseudomyxoma Peritonei. For more information on this research, contact :

Paul H. Sugarbaker, M.D., F.A.C.S.
Director, Surgical Oncology
The Washington Cancer Institute
Washington Hospital Center
110 Irving Street, NW
Washington, DC 20010
Phone: (202) 877-3908
Fax: (202) 877-8602
E-mail: ads1@mhg.edu
Home Page: <http://www.medlantic.mhg.edu/SOA/soahome.html>

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.

For information about clinical trials being conducted at the National Institutes of Health (NIH) Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

TEXTBOOKS
Sugarbaker, P. Intraperitoneal chemotherapy and cytoreductive surgery. 2nd ed. Ludann Press. 1995.

Sugarbaker P. Cancer of the appendix and pseudomyxoma. In: Current Therapy in Colon and Rectal Surgery: BC Decker, Inc;1990:295-301.

JOURNAL ARTICLES
Galani E, et al. Pseudomyxoma peritonei: the ‘controversial’ disease. Int J Gynecol Cancer. 2003;13:413-8.

Van Ruth S, et al. Pseudomyxoma peritonei: a review of 62 cases. Eur J Surg Oncol. 2003;29:682-88.

Jivan S, Bahal V. Pseudomyxoma peritonei. Postgrad Med J. 2002;78:170-72.

Jackson SL, et al. Gelatinous ascites: a cytohistologic study of pseudomyxoma peritonei in 67 patients. Mod Pathol. 2001;14:664-71.

Sugerbaker PH, et al. Pseudomyxoma peritonei syndrome. Adv Surg. 1996;30:233-79.

Gough DB, et al. Pseudomyxoma peritonei: long-term patient survival with an aggressive regional approach. Ann Surg. 1994;219:112-19.

Smith JW, et al. Pseudomyxoma peritonei of appendiceal origin. Cancer. 1992;70:386-401.