Knot on babys head?


My little one is 10 months old .. when she was born via csection, she wouldnt drop at all; has had a small knot on the side of her head . Feels like a pellet.. her ped said it would be fine by 2 months, 2 months came , still there . Said four months , four months came still there . Basicly continued and then was told sometimes it could take longer . I'm suppose to monitor it , if it gets bigger , her ped wants to know immediately..but until then no tests was necessary....anyone have any similarities?