I was seen earlier today for a grape sized mass in my lower back. The mass is soft, movable, and non-painful. Almost immediately, the doctor told me that it was a lipoma and not to worry about it. I was told to watch it and wait to see if it changes but advised that it probably wouldn't.

Is it safe to take someone's word on something like this without having any sort of imaging done? I am not sure how doctors know when to scan and when not to. Any help or advice would be appreciated.