Lesions On Your Kidney: Symptoms, Complications And Treatment

If your doctor has diagnosed you with one or more kidney lesions, you probably have many questions about what this type of diagnosis really means. Like most people, you probably want to know whether a lesion on your kidney is something serious. If it is, you want to know what treatments are available to address your particular health issue.

You may also wonder whether having a lesion on your kidney automatically means you have cancer or whether it means something else.

It's important to remember that "lesion" is simply a term used to describe abnormal tissue. Kidney tissue can become abnormal for a variety of reasons. These reasons may include cancer, infection, or kidney disease.

It's perfectly normal to have many questions after your doctor has examined your kidneys, and the examination and/or the testing results report some abnormality. The best way for you to start to address the issue is to relax, take a deep breath, and learn more about what a kidney lesion diagnosis means for your health.

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Why are the kidneys so important?

Your kidneys perform several important functions for your overall health. One of the most important things your kidneys do is to continually filter your blood, removing certain waste materials and extra water from your bloodstream.

Your kidneys also stimulate your bone marrow to produce a steady supply of red blood cells that circulate around your body. Your kidneys also make certain hormones that are important in controlling your blood pressure.

When your kidneys are functioning normally, all these important processes essentially work without any effort on your part. If one or both of your kidneys begin to malfunction, some of their important functions could be compromised. 

What is a kidney lesion?

A kidney lesion is a generic term to describe an area of kidney tissue that deviates from normal, healthy tissue. In simple terms, a kidney lesion is kidney tissue that is abnormal in some way. There are quite a few reasons a person may develop one or more lesions on either or both of their kidneys during their lifetime. 

Is a kidney lesion the same as a cyst on your kidney?

It can be abnormal to have one or more cysts on your kidneys as you age, but if this is a new finding or has suspicious features, it may be deemed a “lesion.” 

A cyst on a kidney is simply one type of lesion. A kidney cyst consists of a small sac or pouch filled with a watery fluid or air. Kidney cysts generally fall into two categories.

Simple cysts, also known as individual cysts, are benign and don't cause any damage to the kidneys. There is an inherited condition called polycystic kidney disease (PKD), which results in multiple cysts and enlargement of the kidneys. This is uncommon but may result in kidney failure.

More concerning are any cysts with suspicious material in them apart from water or air. These can become cancerous and need to be followed up. 

Is a kidney lesion the same as a tumor?

A tumor on your kidney is abnormal, so technically, the word "lesion" could be used to describe a kidney tumor. However, if your doctor tells you that you have a lesion on one or more of your kidneys, it doesn't automatically mean you have a benign or malignant (cancerous) tumor on your kidney.

If your doctor finds a lesion and suspects it may be cancerous, they will perform additional testing to confirm their suspicions. 

What if your doctor says you have an angiomyolipoma?

An angiomyolipoma (AML) is a form of a kidney lesion. However, it's more commonly referred to as a (benign) kidney tumor. An AML develops when some of the cells in a kidney begin to grow abnormally, eventually forming a mass.

This abnormal cell mass is benign, meaning it's a non-cancerous tumor. If you have a small AML, it may not produce any symptoms at all. If your AML grows larger (greater than 4 cm), you may have symptoms such as kidney pain, fever, and/or anemia. The larger your AML, the more likely you'll require treatment (surgery) to reduce its size to a more manageable level.

Does having a lesion on your kidney mean you have kidney disease?

Kidney disease is defined as any illness that results in impaired renal function. The most severe form of this disease is referred to as kidney failure. While simple cysts could be described as kidney lesions, they do not cause renal dysfunction; therefore, it does not mean you automatically have kidney disease. 

If your kidney lesions are causing damage to your kidneys, then yes, your particular lesions could be a form of kidney disease, or they may be unrelated. 

Kidney disease can be acute or chronic. Acute kidney disease or failure is when the kidneys have lost their ability to properly filter blood within a few hours or days. Chronic kidney disease (CKD) occurs when the kidneys gradually lose their ability to properly filter blood over a much longer period.

Some people have had chronic kidney disease for years. End-stage kidney disease or kidney failure does require continual treatment in the form of kidney dialysis or a kidney transplant if a compatible donor kidney becomes available.

What are the symptoms associated with having a kidney lesion?

The symptoms that may arise from having a kidney lesion will vary, depending upon the cause of the lesion.

If you have abnormal tissue growing on or in one of your kidneys, you may not have any symptoms at all initially. Over time, you may notice symptoms such as blood in your urine and/or swelling due to water retention. The latter may occur because your kidneys are beginning to struggle to remove the excess water from your bloodstream.

Another symptom that may be associated with the development of kidney lesions is lower back pain. If your kidney lesions are due to a form of kidney cancer, you may also notice symptoms such as extreme fatigue, noticeable weight loss, and/or pain in your side.

If you are developing kidney disease, in addition to feeling very tired and having blood in your urine, you may also have difficulty sleeping at night. Some people with kidney disease report feeling the urge to urinate more often, and when they do, they pass foamy urine.

Your skin may be dry and itchy. You may have a poor appetite and experience muscle cramping due to an impairment of the delicate balance of electrolytes that the kidneys normally handle.

Are kidney lesions serious?

This depends upon the cause of the abnormal tissue. If your abnormal tissue is due to a simple cyst, for example, then it shouldn't affect you at all. On the other hand, if it is due to cancer, it should be treated as quickly as possible, as some lesions can be cut out. 

What percentage of kidney lesions turn out to be cancerous?

If your doctor has defined your kidney lesion as a tumor, 20–30%¹ of kidney tumors turn out benign growths. This means the remaining 70–80% of lesions (that are defined as tumors) are considered cancerous.

The larger the tumor (greater than 4 cm), the more likely the tumor is cancerous. Even so, only one-third of cancerous kidney tumors are considered to be aggressive. The remaining two-thirds are labeled as "well-behaved" or low-grade tumors. If detected early, they can be excised, which might be curative.

The lowdown

By now, you've learned that receiving a diagnosis of kidney lesions may or may not indicate a more serious health issue. Your doctor is the best person to advise you on whether you could benefit from further testing.

If you do need further testing, and the additional tests reveal you have an issue with your kidneys, your doctor is a great resource of information. They can answer any questions you may have about treatment and/or refer you to another physician whose primary focus is specializing in the management and treatment of your specific kidney issue. 

As you're going through your medical journey, don't be afraid to ask questions along the way. Your doctor(s) are highly-trained professionals prepared to field your questions. They understand that the more knowledge you acquire about your condition, the more you'll be able to calm your fears and focus on regaining your health.

  1. Kidney cancer diagnosis | Johns Hopkins Medicine

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