What Is Renal Medullary Carcinoma?

Medically Reviewed by Neha Pathak, MD on December 28, 2022
Written by Kristen Fischer
5 min read

Renal medullary carcinoma, or RMC, is a rare yet aggressive type of kidney cancer. It usually affects young people -- mostly those who have sickle cell disease or sickle cell trait and have African ethnicity. But it can affect you even if you don’t have them.

RMC is a rare kidney cancer. The most common type of kidney cancer is renal cell carcinoma. RMC is a type of renal cell carcinoma. Less than 1% of all renal cell carcinoma cases are classified as RMC.

Scientists and doctors aren’t sure exactly what causes RMC.

RMC often happens when red blood cells change into a sickle shape in the part of the kidney known as the renal medulla. The formation of the sickle shape can block the blood supply there.

This can damage the INI1 gene in the renal medulla cells, causing RMC. INI1 is also known as the SMARCB1 gene. When researchers look at RMC tumors, they see that this gene is missing from them. So they look for the INI1 to see if a tumor is RMC or another type of tumor.

Almost all people with RMC have a blood disorder that makes red blood cells sickle (or gather together in the shape of a sickle. The blood disorder is called sickle cell disease. People with RMC may also have the sickle cell trait, which means they have the genetic material for sickle cell disease but not the actual disease.

Having sickle cell trait or sickle cell disease is known as a sickle hemoglobinopathy. RMC doesn’t happen in sickle hemoglobinopathies that don’t cause red blood cell sickling.

Sickle cell disease is when red blood cells are sticky and form the shape of a sickle. The sickle cells die early and lead to a red blood cell shortage.

Researchers have found a few cases of RMC in people with sickle cell anemia – that’s another sickle blood disorder.

There’s another common factor in most people who have RMC: Their tumors don’t include the INI1 gene, which stops cells from turning into cancer.

It’s tough for doctors to tell who will get RMC. There aren’t other indicators or environmental risk factors. You’re not at a higher risk for getting RMC if you have a family member with it.

People can get RMC if they have sickle hemoglobinopathies, but they don’t have to have them to develop RMC. In rare cases, people without sickle blood disorders can get a subtype of RMC known as “renal cell carcinoma, unclassified with medullary phenotype” (RCCU-MP).

RMC happens in men more than women. It is more likely to affect the right kidney (but it can affect the left in those with RCCU-MP). People are usually diagnosed between 11 and 39 years old.

BecauseRMC may be more treatable if it’s diagnosed early, young Black people should be aware of the symptoms and contact their doctors if they have them. This is especially true for those who have sickle cell disease or sickle cell trait. But, again, you don’t have to have them to develop RMC. So pay attention to your symptoms – not just whether or not you have a sickle cell hemoglobinopathy.

RMC is an extremely rare tumor that makes up 0.5% of all kidney cancers. There may be more cases than researchers know of because it can be hard to tell the difference between RMC, collecting duct carcinoma, and other aggressive kidney tumors.

The subtype of RMC, RCCU-MP, is even more rare than RMC. (Again, this shows up in people without sickle cell trait or disease, and in those who don’t have African ethnicity.) Unlike most RMC cases, it doesn’t only happen in the right kidney, and it can affect older people.

The most common symptoms of RMC are:

  • Pain in the kidney area
  • Blood in the urine
  • Mass in the stomach area (usually on one side)
  • Unintentional weight loss
  • Fevers
  • Night sweats

After you report any symptoms to your doctor, a specialist would then do an ultrasound. That’s a noninvasive procedure that gives the doctor an idea of whether or not there’s a potential tumor (or mass).

If they see a mass that may look like cancer, they may request a CT scan or MRI to get a better look. After looking at those images, the doctors can tell if the mass could be cancerous.

If they think so, the doctor will do a biopsy to look at tissue from the tumor. This is a procedure where they will numb the area of your body over your kidney put a needle into the tissue, then remove a small piece of tissue and test it under a microscope. When they do this, they can see exactly what’s in – or not in – the cells.

They will see if it has INI1 – that gene that can stop cancer cells from forming that is found in other cells but doesn’t exist in RMC tumor cells.

If there is no INI1, the cancer will be diagnosed as RMC. If there’s no INI1 and the patient doesn’t have a sickle cell hemoglobinopathy, the cancer will be diagnosed as RCCU-MP. If there’s INI1 in the cells, it’s not RMC.

Treatment can include surgery, chemotherapy, or radiation therapy. Chemotherapy usually is the first treatment because the cancer is so aggressive.

Researchers are looking at new ways to treat RMC, and there are some small studies on potential targets for treatments.

There are no known ways to prevent RMC or to find out if you have it if you don’t have symptoms. Your best bet may be knowing if you have a sickle cell hemoglobinopathy and monitoring yourself for symptoms.

One study reports an average survival time of 13 months. Other studies have shown longer survival with different treatments. Because the cancer is rare, there aren’t as many studies on it compared to other types of cancer. A lot of the knowledge is based on trying to connect the dots from individual cases.

By the time most people are diagnosed, the cancer has spread to the lymph nodes or other organs.

In most patients, RMC spreads to the lymph nodes, but it can also spread to the lungs, liver, and bones. It usually does not affect the brain.

If you know that you have sickle cell trait or sickle cell disease, and are aware of any symptoms (and seek treatment immediately), you may be able to detect it sooner and have a better outcome.