Can Steroid Injection for Rhinoplasty Cause Hump to Form on Bridge?

The steroid injection won't "create" a new bump or hump but if there was an underlying bump or hump that was "masked" by the swelling or thickness of the skin, after steroid injection this can be "unmasked" or "unveiled"!

No, the cortisone shot will not create a hump on the nose. Cortisone shots will thin the dermis of the skin if injected into the skin level. The cortisone injections are placed in the subdermal plexus to decrease fluid retention and scar formation. If the bump is both cartilage and/or bone, it will not go away and you have to undergo a minor revision to file that down.

Bumps on the nose after rhinoplasty can occur.  This may be more noticeable as the swelling comes down.  AS for the steroid injnections, some use them to decrease swelling. Steroids do not cause bumps as a common side effect.