Cancer is a very complex disease. I had to learn that the hard way. first my wife got diagnosed with breast cancer and later on I was diagnosed with kidney cancer. If there is one thing I came to understand is that everybody's cancer is very different. The the same applies to kidney lesions. You may have seen the expression 'lesion on kidney' on pathology reports - it wasn't on mine. My kidney was completely overshadowed by a large 7cm mass and way beyond the stage for a kidney lesion.

So basically, a lesion is and area that has been identified as abnormal tissue. The problem is, without further testing and diagnosis a kidney lesion can mean anything from "nothing to worry about" to "very serious". It depends on their exact location and their rate of growth. The truth of the matter is you might even have a kidney lesion without even knowing it. But other patients may experience symptoms that are indicative of serious conditions such as Renal Cell Cancer (kidney cancer) for example, which include, blood in the urine and a dull pain in both sides of the lower abdomen. 

A kidney lesion can either be benign or malignant. Obviously, if it's malignant then there is evidence of a cancerous disease. However, it could also be a result of a trauma, kidney malfunction or infection.

Lesions are usually detected via ultrasound or a CAT-Scan. If they are cancerous there is usually also evidence of a cancerous mass in one of the kidneys. And if a chronic infection is the cause then a CAT-Scan or Ultrasound usually indicates scarring of the organ. This can lead to impairment of the kidney function and the aforementioned symptoms. 

Typically, before a lesion is being detected, the patient does experience unusual signs which are then being evaluated by a health care professional. Like in my case, the first step is a urine-analysis to check on whether there is evidence of blood and or malignancy. In a next step and ultrasound or CAT-Scan will help to locate the exact location of the lesion on the kidney. However, in order to conclusively determine whether or not the abnormal tissue is cancerous, a biopsy needs to be conducted. One way to do that (and I had that done) is via a so called cystoscopy. A small tube is being inserted into the ureter. inside that tube is a camera and a medical tool that is being used to take a sample of the tissue in question. The sample is then being sent to a specialize lab for further analysis.

Once the cause of the kidney lesion is determined, the treatment options will be discussed. It the tissue came back benign, it is not uncommon for doctors to recommend a "wait and see" approach, if tolerable to the patient. If it's kidney cancer, then it will obviously all depend on the stage of the disease.

Picture of a kidney lesion: