What is the cause of these discoloured digits?
Raynaud’s or a different reaction?

You could be forgiven for pointing the finger at Raynaud’s phenomenon as the cause of this patient’s patchy palm and digits, but the discolouration is actually down to a side effect of a steroid injection.
As it happens, the redness is the affected area in this case, as opposed to the characteristic white distal extremities of Raynaud’s.