Hi. My 12 Y.o. Daughter Has Had A Small 0.25cm

Hi. My 12 y.o. daughter has had a small 0.25cm size hard light skin color bump on her upper back shoulder that has increased in size to 0.5cm in 4yrs. Upon her visit to 2 Dermatologist we were told it similar to calcium deposit nothing to worry about? what is this. what do I need to do about it/