To tell you the truth, I never understood what this meant either.  I
just remember a diagram from medical school days which showed sample
incisions "along skin lines" on the breast.  The lines went in the
direction: chest wall towards nipple.  Thus a circumferential incision
(even a very short one) is not along skin lines.

If this is wrong due to my ever increasingly failing memory, the idea
was *not* to make circumferential incisions, even partial
circumferential incisions.

Jack Newman, MD, FRCPC