Biopsy Results

Does anyone know what pushing border means on a biopsy? I had a shave biopsy of a brown spot that was years ago diagnosed as some type of keratosis on biopsy. Recently that same brown patch came back again . I also had two new thingies show up. One on side of nose and the other on knuckle. These are both pinkish, size of an eraser(donut shaped) with pinpoint indent . My dermo did shave biopsy on the side of nose one and the other brown patch that came back on my face. They both came back as relatively uniformly sized aggregations of atypical basaloid epithelial cells exhibiting a pushing border. So just had surgical removal with stitches yesterday. He froze the brown one again a few weeks ago and that is gone. He will biopsy the one on knuckle when I have the stitches taken out from side of nose nodular basal cell one.
My question is why did the brown rough patch come back as the nodular type of basal cell when it doesn't look nodular as in the one by the fold of my nose? My other question is what does "pushing border" mean on the shave biopsy.
Thank you for any info.