Bony lump on top of a child right foot ?

Bony exostoses.: Bony exostostes are bone growths do to bone injury, or arthritis. The are common, particularly at the tarsonavicular joint. If there is no pain, i would not worry.

See a doctor: All lumps should be evaluated. Hopefuly, it is a benign condition like a ganglion. But, it really needs to be checked out and contents either fluid or solid material should always be biopsied. (in my opinoin).