A lumpectomy knife set including a main knife having at least one first planar wall extending between an upper edge and a knife edge with the at least one first planar wall defining a first geometric shape about a first through opening. A margin knife has at least one second planar wall extending between an upper edge and a knife edge with the at least one second planar wall defining a second geometric shape about a second through opening larger than the first through opening. The second geometric shape complements the first geometric shape such that the margin knife is concentrically positionable about the main knife with a margin gap between the main knife and the margin knife.
