Rhabdoid Tumour of the Kidney

Rhabdoid tumour of the kidney is one of the most aggressive childhood cancers, striking primarily infants and toddlers with devastating speed and intensity.

C0206743
C64
Rhabdoid tumor of the kidney, RTK, Malignant rhabdoid tumor of the kidney, Renal rhabdoid tumor

• Kidney

Table of contents

• What is a rhabdoid tumour of the kidney?
• Who is affected?
• Genetic causes
• Signs and symptoms
• Diagnosis
• Treatment approaches
• Outlook and prognosis

What is a rhabdoid tumour of the kidney?

A rhabdoid tumour of the kidney is a rare, fast-growing cancer that forms in the kidneys of young children^[1]. This type of cancer is part of a larger group called rhabdoid tumours, which can develop in different parts of the body. When these tumours grow specifically in the kidney, doctors call them rhabdoid tumours of the kidney, or RTK^[4].

The name “rhabdoid” comes from how these cancer cells look under a microscope. They resemble cells called rhabdomyoblasts, which are cells that normally develop into muscles^[1]. However, despite this resemblance, rhabdoid tumours are not actually related to muscle tissue.

What makes these tumours particularly dangerous is how quickly they grow and spread. Rhabdoid tumours of the kidney are known to metastasize, which means they spread to other areas of the body very rapidly^[1]. This aggressive behavior makes them extremely difficult to treat.

Rhabdoid tumours can also develop in other soft tissues throughout the body, such as the liver, lungs, and skin. When they grow outside the kidney, doctors may call them extrarenal malignant rhabdoid tumours or MRT^[4]. When these tumours form in the brain or spinal cord, they are called atypical teratoid rhabdoid tumours, or ATRT^[1].

Who is affected?

Rhabdoid tumour of the kidney mainly affects babies and very young children. These tumours most commonly occur in infants between 11 months and 18 months old^[1]. The average age at diagnosis is 15 months old^[2].

This cancer is extremely rare. Some studies suggest that fewer than 1 in 1 million people will develop this type of cancer^[1]. In the United States, there are approximately 20 to 25 new cases of malignant rhabdoid tumours diagnosed each year^[2]. In children, rhabdoid tumours of the kidney account for 0.9 to 2% of all kidney tumours^[5].

While the condition rarely occurs in adults, it has been reported. The peak incidence is between 1 and 4 years of age^[4].

Children, typically in their first year of life, may sometimes present with more than one primary rhabdoid tumour at the same time. These infants typically have a tumour in the central nervous system and one in the kidney, or tumours in the brain along with one in the lung or liver^[4]. Because of this possibility, brain and spine imaging studies should always be performed when a child is diagnosed with a kidney or other soft tissue rhabdoid tumour^[4].

Genetic causes

A genetic mutation causes most rhabdoid tumours of the kidney. Specifically, a change in a gene called SMARCB1 is responsible for the vast majority of these tumours^[1]. This gene is also known by other names: INI1, SNF5, and BAF47^[2].

The SMARCB1 gene is what doctors call a tumor suppressor gene. This means it normally makes a protein that helps control how cells grow. When this gene works properly, it helps prevent tumours from forming^[1]. However, when a mutation occurs in this gene, it loses its ability to suppress tumour growth, which can lead to the rapid growth of cancer cells.

In rare cases, rhabdoid tumours can also develop due to changes in another tumour suppressor gene called SMARCA4^[1].

While some children are born with a mutated gene inherited from a parent, the majority of rhabdoid tumours occur in children with no biological family history of the condition^[1]. These cases result from a new genetic mutation that happens spontaneously. When the mutation is inherited, children may be at risk of developing tumours in more than one location in the body^[1].

Because of the genetic nature of this disease, as part of your child’s care, they may have a genetic evaluation to determine the likelihood of passing on the mutated gene^[1].

Signs and symptoms

The symptoms of rhabdoid tumour of the kidney depend on the child’s age and where the tumour is growing in the body. Often, the first sign that a child has this tumour is the discovery of a lump or mass in the child’s abdomen^[2]. Because these tumours occur most frequently in infants, the child may not show any signs of pain or discomfort beyond fussiness, potentially making early diagnosis difficult^[2].

Symptoms usually begin near where a tumor is growing in the child’s body and may include a lump on the child’s belly, difficulty breathing, or nerve paralysis. Signs and symptoms may develop quickly because the tumor spreads rapidly^[1].

A child with rhabdoid tumour of the kidney may experience the following symptoms:

• Fever
• Abdominal pain or a palpable mass in the abdomen
• Blood in their urine, which doctors call hematuria^[1]
• Difficulty urinating^[2]
• Nausea and vomiting
• Swollen lymph nodes
• Irritability or fussiness
• Decreased appetite
• Unusual sleepiness
• Weight loss
• Diarrhea^[5]
• Abdominal distension^[5]

In some cases, laboratory tests may reveal low hemoglobin levels, elevated inflammatory markers, or changes in kidney function^[5]. High blood calcium levels, known as hypercalcemia, may also be present at diagnosis^[7].

Diagnosis

When doctors suspect a child has a rhabdoid tumour of the kidney, they will perform a physical exam and ask about the child’s symptoms^[1]. The doctor will then request several tests to determine a diagnosis and whether the tumour has spread to other parts of the body.

Diagnostic procedures may include:

• Ultrasound: This test uses high-energy sound waves to create images of the inside of the body. An ultrasound can reveal a mass in the kidney and show details about its size and characteristics^[5].
• Computed tomography (CT) scan: A CT scan creates detailed, cross-sectional images of the body. This test can show the size and location of the tumour, whether it has spread to nearby structures, and if there are any enlarged lymph nodes^[5].
• Magnetic resonance imaging (MRI): An MRI uses magnets and radio waves to create detailed pictures of the body’s organs and tissues.
• Biopsy or tissue sample: A biopsy involves removing a small piece of the tumour to examine under a microscope^[2]. This is the definitive way to diagnose a rhabdoid tumour.
• Blood tests: These may include a complete blood count and tests for kidney function and calcium levels^[5].
• Urinalysis: A urine test can check for blood or other abnormalities.

If a biopsy is taken, the sample will be tested for mutations in the SMARCB1 gene, which is turned off in nearly all rhabdoid tumours^[2]. If a mutation is found, the child’s doctor may recommend additional tests.

Because rhabdoid tumours can occur in multiple locations, imaging of the brain and spine is essential when a kidney tumour is diagnosed^[4]. Similarly, if a brain tumour is found, imaging studies should be done to rule out a kidney tumour.

Treatment approaches

Because rhabdoid tumour of the kidney is so rare and aggressive, there is no defined standard of care^[2]. Treatment options may be tailored to the child’s specific situation. The child’s doctor and other members of the care team will discuss the options in depth with the family. Prompt medical attention and aggressive therapy are important for the best outcomes^[2].

Treatment typically involves a combination of the following approaches:

Surgery: In most cases, the first step in treating rhabdoid tumour of the kidney is surgery^[2]. A surgeon will try to remove as much of the tumour as possible. Depending on the size and location of the tumour, part of the kidney or the entire kidney may be removed. The child may undergo a radical primary ureteronephrectomy with regional lymphadenectomy, which means removing the kidney, ureter, and nearby lymph nodes^[5].

Chemotherapy: Aggressive chemotherapy usually follows surgery^[2]. Chemotherapy uses powerful drugs to help kill fast-growing tumour cells. Because these tumours grow so quickly, high-dose chemotherapy is often necessary.

Radiation therapy: Radiation therapy may be given to children older than six months of age. This treatment uses high-energy beams to help shrink and kill the tumour^[2].

Stem cell transplantation: In some cases, doctors may recommend a stem cell transplant. This involves extracting healthy blood cells from the child’s body, followed by administration of drugs to kill cancer cells. After treatment, the healthy cells are returned to the child’s body to help restore normal function^[2].

A doctor may also recommend combining surgery with other treatment options, or combining high-dose chemotherapy with radiation therapy and stem cell transplant for optimal outcomes.

Outlook and prognosis

The outlook for children with rhabdoid tumour of the kidney remains challenging. This cancer is known for being extremely aggressive and difficult to treat. The overall survival rate is low, ranging between 2% and 22%^[5].

Several factors affect a child’s prognosis:

• The size and location of the tumour
• The extent of the disease at diagnosis
• Whether the tumour has spread to other parts of the body
• The tumour’s response to treatment
• The child’s age and overall health
• The child’s tolerance of medications, procedures, or therapies
• Availability of new treatments^[1]

Children with metastatic disease, meaning the cancer has spread to other parts of the body, face particularly poor outcomes. Metastatic rhabdoid tumours are resistant to conventional treatment, with less than 20% cure rate^[4]. Most children diagnosed with a rhabdoid tumour do not live more than a few years^[1].

Even with intensive treatment strategies that combine surgery, chemotherapy, and radiation, relapse is common and often occurs quickly. In one reported case, a child died 5 months after surgical resection despite receiving adjuvant chemotherapy^[5].

However, research is ongoing. Diverse clinical trials are being conducted with the hope of improving the prognosis of rhabdoid renal tumours^[5]. Discoveries of clinical and molecular characteristics and the exploration of experimental therapeutic approaches are opening new perspectives for treatment.