Understanding Your Type of Kidney Cancer
The kidney is made up of many layers of cells. Kidney cancer can affect any one or all of these layers.
Renal cell carcinoma
The main type of kidney cancer is called renal cell carcinoma (RCC). It begins in a layer of tissue called the renal tubular epithelium. More than 9 out of 10 malignant kidney tumors are this type. If you have this type of kidney cancer, you may have more than one tumor in one or both kidneys. These may be quite large by the time they are diagnosed. But most are found before they have spread, called metastasized, to other organs. If you have renal cell carcinoma, you will have one of five types. The pathologist identifies these types by looking at the cancer cells under a microscope. There appears to be a link between the type of renal cell carcinoma and how it behaves:
Papillary. This is the second most common type of RCC, accounting for 10 to 15 percent of cases. The cells from papillary tumors appear pink from the dye used to prepare the tissue before examination. These cancers also form tiny fingerlike projections, which gives them a tubular appearance.
In some cases, the term sarcomatoid may be used to describe certain kinds of kidney cancer. Clear cell or papillary kidney cancer may be called sarcomatoid when the cancer cells resemble sarcoma cancer cells. Some experts believe that sarcomatoid kidney cancers are more difficult to treat.
Other types of kidney cancer
There are other less common types of kidney tumors than RCC. These types include the following:
Noncancerous kidney tumors
There are also several types of benign (noncancerous) kidney tumors, including renal cell adenomas, renal oncocytomas, and angiomyolipomas. These tumors may still affect kidney function and can cause pain and other symptoms, but usually they do not spread to other organs.