Not all tumors discovered in the kidney need to be surgically removed. Small, benign tumors (also called angiomyolipomas) or lesions which are not likely to develop into aggressive cancer can be observed. Also, patients who are poor surgical candidates because of multiple health problems or advanced age maybe candidates for active surveillance. For these carefully selected group of individuals, periodic evaluation of their kidney tumors using ultrasound, CT scan or MRI allows for monitoring for growth and spread of the disease perhaps avoiding more aggressive surgical treatment.