Lump after exisional biopsy

hello ladies,

Because everyone has so much experience i thought let me ask my question on this site

I had a benign lumpectomy (excisional biopsy) may 2018. After surgery immediately there was a ridge below the scar. Now a year later i feel another hardish rubbery thing (scar tissue??) above the ridge which is painful when rubbing it too much. Went for an US and she said just a bit irregular but totally not concerned. No malignant features. So i am a bit less stressed but still a bit anxious... Do you know how they can see the difference? To me it looked as a cancerous mass but the report stated no mass. She is a great radiologist so i quess she knows what she is doing.

And can scar tissue a year after surgery develop??

Thank you all for the response!