How old is the child?
How old is the child with swollen hands? There are a lot of reasons hands may be swollen and the concerns could depend on the age.
Babies look like their hands are puffy sometimes because they naturally store fat in that area (their little feet too!).
Toddlers might look that way if they have been injured, like with dropping something on them.
With older kids you really want to figure out where it is swollen. Is it close to the joint? In the fatty areas (like corners of the palms)? Closer to the joint I would ask the pediatrician, but in the fatty areas I would just keep an eye on it.