Hi, Thanks for writing in to us. Renal angiomyolipomas are benign tumors containing fat, muscle and blood vessels. The treatment depends on the size of the angiomyolipoma. Small asymptomatic lesions ( 4 cm) tend to remain stable but should be periodically evaluated. Medium-sized lesions (4-8 cm) have the most variable behavior. These lesions should be followed closely with serial imaging studies, and if significant changes in size or symptoms are noted, or the patient is at risk for flank trauma, elective intervention should be initiated promptly to increase the chances of renal salvage. Large asymptomatic angiomyolipomas ( 8 cm) will most likely become symptomatic and should be treated electively prior to the development of symptoms and potential complications. Since in your mother the tumor is measuring 6.7 cms, there is time to wait and watch over next 6 months, for any growth in size and urinary symptoms before thinking about surgical treatment.