What Is a Retroperitoneal Tumor?

A retroperitoneal tumor is an abnormal and rare growth that develops inside part of the abdominal cavity known as the retroperitoneal space. As the retroperitoneal space is hidden toward the back of the abdomen and the organs there are quite mobile, a retroperitoneal tumor can grow quite large, shifting organs out of its path, before being discovered. Symptoms such as an enlarged belly and abdominal pain may eventually develop. Although retroperitoneal tumors can be benign, or harmless, most often they are cancerous. Surgical removal is the most common treatment, although tumors can recur.

The peritoneum is a thin sheet of tissue that lines the inner walls of the abdomen, covering and enclosing the abdominal organs. At the rear of the abdominal cavity there is an area where the peritoneum does not completely enclose the organs, and this is known as the retroperitoneal space. The kidneys, adrenal glands, large blood vessels and parts of the gut lie in this space, where they are only covered by peritoneum on one side. As the tumor develops, it can affect any of these retroperitoneal organs by pushing them out of place, crushing them or invading their tissues.

Diagnosing a retroperitoneal tumor usually involves a CT scan or an MRI scan, which can show an image of the growth and its effect on surrounding structures. Most frequently, the type of tumor is what is known as a sarcoma, which arises from the body's soft tissues, such as skin and muscle. A retroperitoneal sarcoma is cancerous, and the patient's outlook depends on whether the tumor can be removed completely and whether it has grown into surrounding organs or spread into other areas of the body.

If a tumor is cut out whole before it has had a chance to spread, the patient will have a more positive prognosis, although there is still the chance of recurrence. Some tumors invade major blood vessels and nerves, and this can make it impossible to remove them completely. When a retroperitoneal tumor grows into one of the kidneys, the kidney can be removed. Patients can survive if the remaining kidney is functional.

As well as surgery, methods such as radiotherapy can be used to treat this type of tumor. Radiotherapy is usually given before or after surgery to shrink the tumor or to kill any cells which may have been left behind after an operation. Chemotherapy has not been proven to work in treating this type of tumor, although research is ongoing.