Mole growing back into scar tissue? (Photo)

I had a mole removed from my shoulder 10 years ago. It was benign but left scar tissue. The mole is now growing back into the scar. I saw a dermatologist about 1 yr ago and he did not seem concerned about it. It seems to be darker brown, more splotchy since that visit and it is slowly expanding with somewhat jagged edges. It's a little bigger than a pencil eraser, but seems to be confined to the scar tissue. Will be returning to dermatologist soon but wanted to ask about it in the meantime. Thanks!