What does it profit having marks? And why would they not be anatomically correct?
Let us remember that it is our suffering that benefits the Church, when it conforms to the suffering of Christ. The Biblical example is St. Paul who had a poor vision and a "thorn in his side":
7 And lest the greatness of the revelations should exalt me, there was given me a sting of my flesh, an angel of Satan, to buffet me. 8 For which thing thrice I besought the Lord, that it might depart from me. 9 And he said to me: My grace is sufficient for thee; for power is made perfect in infirmity. Gladly therefore will I glory in my infirmities, that the power of Christ may dwell in me. 10 For which cause I please myself in my infirmities, in reproaches, in necessities, in persecutions, in distresses, for Christ. For when I am weak, then am I powerful.(2 Cor. 12)
continue in the faith, grounded and settled, and immoveable from the hope of the gospel which you have heard, which is preached in all the creation that is under heaven, whereof I Paul am made a minister. 24 Who now rejoice in my sufferings for you, and fill up those things that are wanting of the sufferings of Christ, in my flesh, for his body, which is the church: 25 Whereof I am made a minister according to the dispensation of God
(Col 1)
What do we see here? The sign of suffering is a form of grace; it is applied to the suffering of Christ; it builds up the treasure of grace in the Church. Nowhere does the sign anatomically conforms to Christ. One wracked with cancer can, God willing, apply his pain to the pain of the scourging or the Crucifixion. If cancer anatomiically unrelated to the Holy Wounds can do it, then why demand anatomical correctness in the stigmatic wounds?