1. A portable compression apparatus for radiologically and graphically locating breast lesions along three dimensional coordinates to facilitate cytological examination and treatment thereof, comprising: means for mounting said apparatus on the film cassette holder plate of a dedicated mammography unit, a top radiolucent compression plate having a cut-out area and a first rectilinear grid scale around the periphery of said cut-out area, a bottom radiolucent support plate having a second rectilinear grid scale around the periphery thereof, said bottom plate being rotatably and removably connected to said mounting means, first means for supporting said top plate and for adjustably positioning said top and bottom plates one relative to the other on either side of said breast; said first and second grid scales constructed and arranged to enable formation of corresponding grid scales on the resulting radiograph, which corresponding grid scales, in conjunction with the representation of the lesion also on said radiograph facilitate subsequent direct graphical representation of the location of said lesion relative to said coordinates within said breast, a needle holder and guide assembly adapted to hold a needle for inserting the tip thereof into the lesion, said assembly being adjustable in its position relative to the lesion to enable accurate and reliable insertion of said tip, means providing support and guidance for said needle along two spaced points of the needle to prevent deflection thereof during insertion of said needle tip, said needle holder assembly including first parallel rails on said top plate having calibrations thereon for adjusting the position of said assembly in the Y direction, a first sliding base mounted transversely on said first rails, said first base having second parallel rails mounted longitudinally thereon and having calibrations thereon for adjusting the position of said assembly in the X direction; a second sliding base mounted transversely on said second rails, and second base having a rod extending vertically therefrom, said rod having calibrations and a slidable needle holder thereon, said calibrations and slidable needle holder for adjusting the position of said assembly in the Z direction; said second sliding base including a releasable bushing having a lumen through which said needle extends, said bushing and said slidable needle holder providing support and guidance for said needle, said second base and said needle holder also permitting release of said needle from said apparatus while maintaining said needle tip at said location.