Mucinous Adenocarcinoma of the Appendix

Mucinous tumors – meaning tumors that produce mucous – of the appendix are quite rare. In normal cases, a thin layer of cells lining the inside of the appendix produce mucous in small amounts. These cells typically die off at the sate rate they reproduce. When tumors occur, the cells reproduce much faster than they die off, creating a mass of cells. These masses of cells are practically the tumors and can produce large amounts of mucous.

There are several types of mucous-producing tumors that can occur in the appendix. These tumors can be either benign or malign. Benign tumors are different from cancerous tumors in the sense that the former don’t usually invade normal tissue or spread to other areas of the body, causing metastasizes. On the other hand, cancerous tumors often do both.

Mucinous adenocarcinoma of the appendix is cancerous, being also the most common type of appendix cancer. Mucinous adenoma, also known as mucinous cystadenoma, is a benign tumor of the appendix. Both types of tumors can release cells into the abdomen and adhere to the inner (peritoneal) surfaces of the abdomen. Some tumor cells may even settle in parts of the abdomen and pelvis. These mucous-producing cells can grow into new tumors and create more mucous.

Even though they are benign, non-cancerous mucous-producing tumors of the appendix may still be fatal if they grow rapidly or create too much mucous. Therefore, they are referred to as low-grade malignancies when they spread into the abdomen. Very large amounts of thick mucous can be produced by both the benign and the malign types of tumors and can cause the abdomen to become bloated with mucinous ascites. In popular language, this phenomenon is known as “jelly belly”. The large amounts of this thick mucous in the abdomen can eventually squash the organs and cause death.

However, with proper treatment, the prognosis for these benign, low-grade mucous-producing tumors is quite high, the survival outcomes being much better than those of high-grade cancerous tumors of the appendix. Below you can read more about mucinous adenocarcinoma of the appendix, the cancerous type of tumor.


  • It is the most common cancer of the appendix.
  • It accounts for about 37% of all appendix cancers.
  • It is a high-grade cancerous tumor that produces mucous, but also more commonly invades soft tissues and organs.
  • It may grow faster and is more likely to metastasize (spread) to the lymph nodes, liver and lungs than the low-grade, benign mucinous adenoma.
  • The medical term for extensive spread of these cancerous tumors into the abdomen is Peritoneal Mucinous Carcinomatosis (PMCA) – commonly known as “jelly belly”.


  • Appendicitis is commonly the first symptom of both the benign and cancerous mucous-producing tumor.
  • Both tumors may cause the abdomen to increase in size or form masses in the abdomen or in the pelvis.
  • In men, the first symptom is sometimes an inguinal hernia.
  • In women, the first symptom is often an ovarian mass.


  • Treatment for mucinous adenoma that has not ruptured and that is confined to the appendix is removal of the appendix.
  • Treatment for mucinous adenocarcinoma confined to the appendix when the appendix has not ruptured is appendectomy and right hemicolectomy, meaning surgical removal of the appendix and up to half of the right side of the colon.
  • Treatment for mucinous adenocarcinoma that has spread extensively into the abdomen consists of cytoreduction surgery to remove mucous and tumor implants in the abdominal cavity, followed by intraoperative hyperthermic peritoneal chemotherapy. This treatment also applies to benign mucinous tumors.
  • Chemotherapy may also be additionally used for treatment of mucinous adenocarcinoma.

Risk Factors

  • Mucinous adenocarcinoma of the appendix is most likely to occur in the 6th decade of life, meaning in individuals ages 60 and beyond.


  • Removal of the appendix for mucinous cystadenoma that has not spread is considered curative.
  • Prognosis for both mucinous adenoma and mucinous adenocarcinoma depends on the grade of malignancy of the mucinous tumor and the success of debulking surgeries in removing all tumors that have metastasized into the abdomen.
  • For high-grade mucinous adenocarcinoma that has spread beyond the appendix into the abdomen, 5-year survival has been stated in some studies to be about 50% when treated with surgery combined with chemotherapy.

While mucinous adenocarcinoma can be cured, the most important factor in this condition’s prognosis is the time of diagnosis. The earlier the tumor is detected, the better chances of survival. Remember to do a periodical checkup, especially if you are over 60 and haven’t had the appendix removed.