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Rhabdoid Tumor Facts

• What is Rhabdoid Tumor?
• What are the risk factors for Rhabdoid Tumor?
• What are symptoms of Rhabdoid Tumor?
• What do we know about the biology of Rhabdoid Tumor?
• How is Rhabdoid Tumor diagnosed?
• How is Rhabdoid Tumor treated?
• What is the prognosis for survival?
• Can Rhabdoid Tumor come back?

What is Rhabdoid Tumor?

Rhabdoid tumor is a rare tumor that was first found to be in the kidney. Over the last several years, research has shown that it can also occur in the central nervous system (brain and spinal cord) as well as other locations outside the kidneys such as the liver, muscle, heart, lung, soft tissues, and skin. If the tumor is in the kidney, it is called "rhabdoid tumor of the kidney", and if it is in the brain or spinal cord it is called "CNS atypical teratoid/rhabdoid tumors (AT/RT)". If it occurs outside of the kidney or brain, it has the longer name of "non-CNS extrarenal rhabdoid tumors".

In the United States, rhabdoid tumor of the kidney occurs only in about 5-10 children each year, so it is extremely rare. Most children are younger than 3 years old when they are diagnosed and only rarely are rhabdoid tumors diagnosed in children older than 5. If the diagnosis is made in a child older than 5, a second opinion by an experienced pathologist is strongly recommended, often with additional special tests to ensure the diagnosis is correct.

Up until now rhabdoid tumors have been treated with the same therapy as other tumors of the kidney. For the first time, the Children's Oncology Group (COG) is treating rhabdoid tumors of the kidney and extrarenal rhabdoid tumors (rhabdoid tumors outside of the kidney) on separate clinical trials. As part of the current trial, all the rhabdoid tumors outside of the brain will be treated with the same chemotherapy, and genetic studies will be performed on the tumor tissue to better understand the biology of rhabdoid tumors.

What are the risk factors for Rhabdoid Tumor?

In recent studies researchers found that approximately 15% of the children diagnosed with a rhabdoid tumor have abnormalities of the INI1 gene in all the cells of their body. Children with these germline mutations of the INI1 gene are often younger than one year old and can have a rhabdoid tumor in more than one location. In almost all cases these germline mutations are only present in the child and not inherited from the parents. This means it is a new change in the gene (called a spontaneous mutation). To date, only two reports have been published where the abnormal INI1 gene was inherited from a parent. The current trial of the Children's Oncology Group will not only look at the biology of the tumor tissue, but will also examine blood cells to look for germline mutations.

What are symptoms of Rhabdoid Tumor?

• Having a fever is common with rhabdoid tumors of all locations
• Rhabdoid tumor of the kidney:
  • Abdominal or flank (side) mass
  • 60% of the children have blood in the urine
  • 70% of the children have high blood pressure
• Rhabdoid tumor of the brain:
  • The child's head might appear larger and the child can feel as if something is pushing on his or her head
  • Neurological changes (brain sensory and output is affected)
  • Seizure
  • High blood pressure

What do we know about the biology of Rhabdoid Tumor?

In the last few years a lot of progress has been made in our understanding of the biology of rhabdoid tumors. First, researchers found that parts of chromosome 22 were missing in rhabdoid tumors of the kidney. This finding led to the identification of the INI1 gene. Through the examination of many tumors originating throughout the body, it was found that almost all the rhabdoid tumors have an error in the INI1 gene. This led to the understanding that tumors with errors or loss of the INI1 gene might represent the same tumor, regardless of the location. These recent findings have allowed researchers to design clinical trials with treatments specific for rhabdoid tumor. This is the first time that rhabdoid tumor has had a specific treatment. So, major steps are being taken forward towards a better outcome for this disease.

How is Rhabdoid Tumor diagnosed?

The first test used to diagnose rhabdoid tumor is often an abdominal ultrasound. A specialized ultrasound called a Doppler ultrasound is done to evaluate if the tumor has grown into the blood vessels. This is followed by a CT scan and/or MRI scan of the abdomen and pelvis to further evaluate the tumor. MRI scans are often done with tumors in the arms and legs. The MRI scan gives a more precise picture of the location and ability for removal of the tumor.

In addition, several imaging studies are used to make sure the tumor has not spread to other organs. A CT scan of the lung allows a doctor to see if the mass in the kidney has spread to the lung which is the most common site for this type of tumor to spread. Chest x-rays (CXR) are often done in addition to CT scans, and are used mostly during and after treatment. A MRI or CT scan of the brain is done to check and see whether or not the rhabdoid tumor has spread to or started in the brain. A bone scan and an x-ray skeletal survey should be done, since the bone is also a common site for rhabdoid tumor to spread.

Your child may be receiving different types of imaging studies if your child's rhabdoid tumor is primarily somewhere other than the kidney (brain, etc.). Most likely your child will not be having an abdominal ultrasound if the tumor mass is not in the kidney or abdominal area.

Once the diagnosis of rhabdoid tumor has been confirmed by a pathologist, the oncologist will evaluate the results and assign a stage to the tumor. Staging means, assessing the characteristics of the tumor, whether it has spread, and if the surgeon was able to remove the entire tumor. The stage of the tumor will determine what type of treatment your child will have.

How is Rhabdoid Tumor treated?

The treatment for patients with rhabdoid tumor consists of the combination of surgery, chemotherapy and radiation. The current recommendations are to remove the tumor first, then continue with chemotherapy and radiation.

Tumors that can not be completely removed or that have spread to multiple places should be biopsied first. Following a biopsy of the tumor, chemotherapy is given to shrink the tumor. Re-evaluation for surgery is done at a later time.

The majority of young cancer patients decide to enter into a Phase III clinical trial. Clinical trials offer the most up-to-date treatments with the best-known results for improvement or cure of rhabdoid tumors.

• Treatment for patients with a removable tumor
• Treatment for patients with a non-removable tumor

What is the prognosis for survival?

The prognosis for patients diagnosed with rhabdoid tumor of the kidney depends on the age and stage of the disease. Patients with stage I or II have had a better survival (42%) than patients with stage III or IV (16%). Older children have had a better survival than younger children. For children older than 2 years of age the survival was 41%, 1 to 2 years of age was 29%, 6 months to 12 months of age was 17%, and below 6 months of age was 9%.

For non-CNS extrarenal rhabdoid tumor (rhabdoid tumors outside of the kidney) the reported survival is 20-25%. The number of reported cases is too small to look at stage and age separately.

Can Rhabdoid Tumor come back?

It is possible for rhabdoid tumor to come back, and it can come back in the original site, as well as new sites. Common places for rhaboid tumors to come back in are the lungs and abdominal area.

Written and reviewed by: Susanne Ragg, MD, PhD; Deannie Lee, MD, PhD; Mary M Davis MD; James Hill, MD; Mercy Odueyungbo, B.S.; Ann Haddix, RN, MSN, CPNP; Jada Paine, MS; Julie Haydon, BS; Michelle Lucke, MPH; Elaine Skopelja, MALS, AHIP; Kellie Kaneshiro, AMLS, AHIP. Amber McMahon, B.S. Date last reviewed: August 2006.