I have a result of renal tract ct,,with 3cm exophytic mass arising from the upper pole of l kidney which looks like a cyst,,is this cancer??

Maybe yes maybe no: If it's truly a cystic lesion and then I will be benign however there are cystic cancers of the kidney the more cystic component has the more likely it is benign let's hope it's a simple retention cyst with just fluid the ultrasound should help determine whether this is fluid maybe you should have a follow-up ultrasound after the CT scan