Cystic renal cell carcinoma (RCC) is a rare form of kidney cancer that accounts for 1 percent to 4 percent of all RCC cases. People diagnosed with this subtype of RCC usually have a good prognosis, or outcome.

In this article, we’ll look at the risk factors and symptoms of cystic RCC, how doctors tell it apart from other types of kidney cancer, and what treatment options may be available.

What Is Cystic Renal Cell Carcinoma?

Cystic RCC is a subtype of RCC in which the tumor is mostly made of a cyst, or a fluid-filled sac. To be classified as cystic RCC, about 50 percent to 75 percent of the tumor must be made up of this fluid-filled area.

Between 5 percent and 15 percent of all kidney tumors have cystic features. These may be benign (noncancerous), or they could be types of RCC that include cysts, such as:

• Clear cell RCC
• Chromophobe RCC
• Papillary RCC
• Multilocular cystic RCC (also called multilocular cystic renal neoplasm of low malignant potential, or MCNLMP)
• Eosinophilic solid and cystic RCC (ESC-RCC)
• Tubulocystic RCC
• Acquired cystic disease-associated RCC (ACD-RCD)

Researchers are still learning more about these different types of kidney cancer and how to best treat them.

Risk Factors for Cystic Renal Cell Carcinoma

People with certain inherited genetic conditions may be more likely to develop cystic RCC. Polycystic kidney disease and von Hippel-Lindau disease can cause kidney cysts and are linked to an increased risk of RCC. These conditions may raise the risk of cystic tumors forming in the kidneys.

Long-term dialysis is also associated with cystic RCC. Dialysis is a treatment that removes waste, toxins, and extra fluid from the blood when the kidneys stop working well. The longer a person is on dialysis, the more likely they are to develop kidney cancer, such as RCC or ACD-RCD.

Other risk factors for cystic RCC include:

• Smoking
• A high body weight or obesity
• Hypertension (high blood pressure)
• Family history of kidney cancer
• Exposure to certain industrial chemicals, such as cadmium or trichloroethylene

Symptoms of Cystic Renal Cell Carcinoma

Like other types of RCC, cystic RCC often doesn’t cause symptoms in its early stages. Many people are diagnosed before they notice anything unusual. But as the kidney tumor grows, symptoms may start to appear. The most common early symptoms include hematuria (blood in the urine) and flank pain (pain in the side or lower back).

If the kidney tumor grows into nearby tissue or blood vessels, additional symptoms and signs may develop. These include:

• A lump or swelling in the abdomen or flank
• Fever
• Night sweats
• Unintended weight loss
• Loss of appetite
• Tiredness
• Swollen legs and feet
• Anemia (low red blood cell count)

Cystic RCC may be less likely to spread to other parts of the body — a process known as metastasis. That means symptoms like shortness of breath or bone pain, which can happen when cancer spreads to the lungs or bones, are less common.

Testing for Cystic Renal Cell Carcinoma

Cystic RCC is often found by accident when doctors are doing tests for an unrelated health condition. This is called an incidental diagnosis.

Because cystic RCC can look like a benign kidney tumor, it’s sometimes hard to tell them apart. To get a clearer picture and avoid a misdiagnosis, your doctor may order more imaging tests such as an ultrasound or a computed tomography (CT), positron emission tomography (PET), or magnetic resonance imaging (MRI) scan.

If imaging shows a mass, your doctor may remove a sample of tissue during a biopsy or surgery. Lab tests on these cells can confirm whether the tumor is cystic RCC, another type of kidney cancer, or benign.

In some cases, you may not get a final diagnosis until after surgery, when doctors can examine the tumor more closely.

Treatments for Cystic Renal Cell Carcinoma

Treatment options for cystic RCC depend on the size of the kidney tumor, the cancer stage, and your overall health.

Surgery

The initial treatment for cystic RCC is surgery — either a partial nephrectomy (removing just the affected part of the kidney) or a radical nephrectomy (removing the entire kidney and some surrounding tissue and fat).

In the past, a radical nephrectomy was often recommended over a partial nephrectomy for people with cystic RCC. Doctors avoided partial nephrectomy because of the belief that opening the cyst during surgery could spread cancer cells and cause a recurrence (return of the cancer). But newer research shows that this risk is very low.

Now more doctors have been using partial nephrectomy to treat smaller cystic RCC tumors. This treatment option helps protect kidney function and is just as effective as a radical nephrectomy. A 2023 study found that people with cystic RCC who had partial nephrectomies had better outcomes than those who had radical nephrectomies.

Cystic RCC usually doesn’t spread to nearby or distant tissue, so surgery may be the only treatment needed. However, if the tumor shows signs that it might recur or spread, your doctor might recommend immunotherapy or targeted therapy.

Active Surveillance

People with small kidney tumors may not need treatment right away. Active surveillance involves watchful waiting to see how the kidney tumor behaves. Your doctor will monitor the kidney tumor with imaging tests to see if it grows or changes. Treatment can start later if needed.

Prognosis for Cystic Renal Cell Carcinoma

Cystic RCC generally has a good prognosis, and many people do well after surgery. Several studies have found that RCC subtypes with cystic features often lead to better outcomes than similar tumors without cysts. Even subtypes that may appear more aggressive under a microscope, such as ESC-RCC, typically grow slowly.

Because cystic RCC is rare, no large studies have specifically tracked this subtype’s survival rate — the percentage of people alive a certain time after diagnosis. However, we do know that most cystic RCCs stay in the kidney and don’t spread. That’s important, because localized kidney cancer has a strong five-year relative survival rate of 93 percent, according to the National Cancer Institute.

Your cancer care team can help you better understand what individual factors may affect your prognosis with cystic RCC.

Get the Support You Need

Receiving a cancer diagnosis — even one with a good prognosis — can feel overwhelming. Many people find it helpful to join a support group. Taking care of your emotional and physical well-being is just as important as treating your cancer. Let your care team know about any symptoms, side effects, or concerns so they can help you feel your best.

Find Your Team

On MyKidneyCancerTeam, the social network for people living with kidney cancer and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with kidney cancer.

Have you or a loved one been diagnosed with cystic renal cell carcinoma? What advice do you have for people newly diagnosed with this type of kidney cancer? Share your experience in the comments below, or start a conversation by posting on your Activities page.