Thank you for the query.
If you are skinny person, you may be able to palpate gall bladder
in this localisation. It should be movable while breathing. Lipoma
is also possible but this would be palpated in the soft tissues of the skin, not inside the abdomen.
mass can be palpated in such way as kidney is more in the back and is covered with plenty of fatty tissues. Moreover, CT would for sure visualize it.
Hope this will help.