What are the different types of kidney mass?

There are many different types of kidney masses, ranging from cysts to adenomas and fibromas. All of them can be classified as benign, meaning noncancerous, precancerous, meaning they can eventually cause cancer, and malignant or cancerous. Most small kidney growths are benign, while larger ones are more likely to be cancerous. Most masses are diagnosed incidentally, as they often cause no symptoms. If treatment is required, there are a variety of options, including watch and wait, medication, and surgery.

Symptoms and diagnosis

Many kidney masses do not cause any symptoms at all, and may be discovered incidentally through an X-ray, computed tomography (CT) scan, magnetic resonance imaging (MRI) study, or ultrasound being performed for another procedure. Those that do cause symptoms can cause unexplained fatigue, blood in the urine, back pain near the ribs, stomach pain, and unexplained weight loss. If a kidney mass is particularly large, a person can feel it through their skin. Sometimes pain in other parts of the body can be a specific sign of kidney cancer, especially if it is in advanced stages and has spread beyond the kidneys. Since kidney stones also cause many of these symptoms, masses are sometimes confused with them, but can generally be distinguished by symptoms, as they also cause fever and a burning sensation when urinating, as well as much more pain.

Once a growth is suspected, health care professions generally refer a person to a urology clinic for testing. While there, the person usually gives a urine sample and a blood sample, and the urethra and bladder may be examined in a procedure called a cystoscopy. Doctors may also do additional MRIs or ultrasounds to learn more about the mass, particularly its size, as this can help them determine whether or not it is likely to be cancerous. A mass about 1.5 inches (4 cm) or smaller has only a 20 to 30% chance of being cancerous, while ones larger than 2.75 inches (7 cm) have about a 90% chance to be cancerous. Health care providers may also take a biopsy, which is a small sample of the lump, to learn more about it. Once they know what the growth is and how big it is, they can recommend a course of treatment.


Many growths are actually cysts, which are fluid-filled sacs in or on the kidney. Cysts are almost always benign, although if they grow large enough, they may need to be removed. However, most of the time they do not affect kidney function and can be left in place. An exception to this is in those with polycystic kidney disease (PKD), in which a person has multiple kidney cysts. This can cause high blood pressure, anemia, liver problems, and long-term damage to the kidneys. It requires ongoing treatment with diuretics and blood pressure medications, as surgery is usually not effective.

kidney adenoma

Renal adenoma is the most common type of benign renal mass, and usually presents as small growths. These tumors are mainly asymptomatic and their cause is unclear. They are sometimes classified as precancerous, and are almost always closely monitored for growth. Many doctors choose to surgically remove renal adenomas to avoid the possibility of them becoming cancerous in the future.

Renal onocytoma

Another relatively common kidney mass is the renal onocytoma, a tumor that can grow very large and often affects other organs. In its early stages, it may not cause any symptoms and is more likely to appear during another procedure or when it grows large enough to press on other organs. It's not entirely clear what causes it, but it is known that people with genetic Birt-Hogg-Dubé syndrome are more likely to get it and that men are more likely to get it than women. A renal onocytoma is also considered precancerous and is most often surgically removed before it can develop into cancer.


Angiomyolipoma is a very rare type of kidney mass that usually occurs as a secondary effect of a genetic mutation. A condition known as tuberous sclerosis often accompanies angiomyolipomas. Patients who do not experience any symptoms related to the tumors are usually watched closely for any changes, but usually do not receive any treatment unless symptoms appear.

Fibromas and Lipomas

Fibromas and lipomas are two very rare types of benign kidney growths, which are often indistinguishable from cancerous growths. It is completely known what causes fibromas or lipomas, but it is believed that lipomas have a genetic link. They can eventually turn into cancer and can then metastasize or spread throughout the patient's body. For this reason, they are usually removed by surgery.


The two most common types of kidney cancer are renal cell carcinoma and urothelial cell carcinoma. It's not entirely clear what causes them, but known risk factors include smoking, obesity, high blood pressure, hepatitis C, and long-term exposure to dangerous chemicals. Treating kidney cancer can be difficult because it doesn't always respond well to chemotherapy or radiation. Surgery is usually recommended if the tumor has not spread, but if a patient is not a good candidate for surgery because a kidney has already been removed or other health problems, radiofrequency ablation or radiofrequency ablation may also be used. cryotherapy. The first is the use of a high-frequency electrical current to kill cancer cells, and the second is to freeze them.

Wilms tumor

Wilms tumor is a rare type of kidney cancer that is most common in children under 5 years of age. Children who develop it generally have a good prognosis, as it is often curable. The symptoms and method of diagnosis for this type of tumor are generally the same as for other kidney masses. In most cases, the tumor is removed, and in some cases, the entire kidney is removed to prevent the spread of cancer.

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