The term kidney mass is obviously quite vague, as
the word “mass” is simply defined as a “quantity
of matter.” This vague term is appropriately used prior to
a kidney cancer procedure being performed, as kidney cancer is a
diagnosis that can only be made after a pathologist examines a part
of the cancerous tissue itself.
Usually, kidney cancer is discovered incidentally
when some type of radiographic evaluation such as a sonogram, CT
scan or MRI has been performed. Less common symptoms of kidney cancer
(see Signs and Symptoms section)
may initiate the radiographic evaluation. In either case, the radiographic
tests can only describe a solid entity in the kidney. With current
radiographic technology, the exact nature of the disease cannot
be established without examination of the tissue itself.
Prior to this tissue diagnosis, the renal mass may
be one of the types of kidney cancer or a non-malignant growth.
For smaller kidney masses (those less than 4 cm or about 13⁄4
inches) up to 20% or 30% of these masses may be a non-malignant
growth. These masses are usually classified as oncocytomas, angiomyolipomas,
complex cyst or a number of other less common growth types. Larger
kidney masses (greater than 7cm or about 3 1⁄2 inches) are
more commonly a type of kidney cancer. Indeed, over 90% of these
growths are malignant in nature.
Another commonly used word regarding kidney masses
is “neoplasm.” Literally translated, the word neoplasm
is a new growth. Neoplasms are divided into malignant growths (also
known as cancer), which have the ability to grow and spread around
the body (metastasize). Non-malignant or benign neoplasms are tissue
masses that grow but are not capable of spreading around the body
(metastasis). It is important to note that a benign neoplasm of
the kidney can grow and cause problems such as bleeding even though
it does not spread by metastasis.