Non-cancerous tumours of the kidney

A non-cancerous, or benign, tumour of the kidney is a growth that does not spread (metastasize) to other parts of the body. Non-cancerous tumours are not usually life-threatening.

Types of non-cancerous kidney tumours

Most of the following types of kidney tumours are non-cancerous. Some researchers think that some of these tumours have the potential to develop into cancer. When pathologists examine kidneys that have been removed to treat a cancerous tumour, they sometimes also find these types of non-cancerous tumours.

Unfortunately, diagnostic tests can’t tell us if a non-cancerous tumour could become cancerous. As a result, non-cancerous kidney tumours are often treated like cancerous tumours.

Papillary renal adenoma

Papillary renal adenoma is the most common type of non-cancerous kidney tumour. It starts in cells that line the tubules in the kidney. These tumours are small, low-grade growths that usually don’t cause any symptoms. They are most often found during an imaging test done for other medical reasons.


Oncocytoma starts in cells of the collecting ducts of the kidney. These tumors can grow as large as 20 cm (8 in). They are most often found in just one kidney, but sometimes they develop in both kidneys at the same time. There can also be several oncocytomas in different places in one or both kidneys. Oncocytomas may be found at the same time as a cancerous tumour, usually a chromophobe renal cell carcinoma.


Angiomyolipoma is a kidney tumour made up of fat, blood vessels and smooth muscle tissue. Even though these tumours are non-cancerous, they can spread into and destroy surrounding tissue. They can also cause sudden bleeding (called hemorrhage) from the kidney into the abdomen. Bleeding is more likely when the tumour is larger than 4 cm (1-1/2 in).

Sporadic angiomyolipoma (also called isolated angiomyolipoma) is the most common type. It usually appears as one tumour in a kidney. Sporadic angiomyolipoma is more common in women.

Angiomyolipoma associated with tuberous sclerosis is the less common type. Tuberous sclerosis is a genetic disorder that causes non-cancerous tumours to form in many organs, including the eyes, skin, brain, lungs, heart and kidneys. Angiomyolipoma associated with tuberous sclerosis often causes more than one tumour to form in both kidneys. The tumours are usually large. Both men and women can have this form of angiomyolipoma. It affects people at a younger age than sporadic angiomyolipoma.

Rare non-cancerous tumours

These types of non-cancerous tumours are rarely found in the kidney:

  • metanephric adenoma
  • metanephric adenofibroma
  • mixed epithelial and stromal tumours (MEST)

Risk factors

There isn’t a known, single cause for most non-cancerous kidney tumours. People with tuberous sclerosis have a higher risk of developing angiomyolipoma in the kidney.


Non-cancerous tumours rarely cause any symptoms. Larger tumours or tumours that are bleeding may cause:

  • pain in the side, back or abdomen
  • a lump in the abdomen
  • blood in the urine


Most non-cancerous kidney tumours are found when an imaging test is done for other medical reasons. If you have symptoms or your doctor thinks you might have a kidney tumour, you will be sent for tests. Tests used to diagnose or rule out non-cancerous kidney tumours include:

  • urinalysis
  • ultrasound
  • CT scan

Imaging tests can’t always tell us if a kidney tumour is benign or cancerous.

Find out more about these tests and procedures.


Non-cancerous kidney tumours are often treated like cancerous tumours. Treatment options for non-cancerous kidney tumours include:

  • surgery (usually laparoscopic surgery)
  • active surveillance (for very small tumours or ones that doctors can tell are non-cancerous based on imaging tests)
  • arterial embolization (for angiomyolipomas)

Find out more about treatments for kidney cancer.


Referring to or having to do with cancer cells that look and act almost like normal cells (differentiated) and tumours that tend to grow and spread slowly.


Having to do with genes or genetics and usually referring to the effect or structure of genes.

For example, a genetic condition is a disease or disorder caused by a mutation (change) in one or more genes.


A procedure that uses an endoscope (a thin, tube-like instrument with a light and lens) to examine or treat organs inside the abdomen and pelvis.

Cells or tissue may be removed for examination under a microscope. Doctors may also use laparoscopy to perform different surgical procedures in the abdomen and pelvis.

The type of endoscope used for this procedure is called a laparoscope.