To dream of a birthmark represents awareness about how unique something about yourself or someone else is. Feelings about being born to do something. A life purpose.
Negatively, may reflect a problem or burden that you notice only effects you. Feeling that some area of your life is stained or cursed by fate.
Example: A man dreamed of seeing a pastor with his back who didn’t know the birthmark was there. In waking life the man felt his local pastor didn’t respect how special his life purpose was as a leader of the church because the pastor was too concerned with miracles and materialism and not enough with responsible messages about charity and hard work. The unseen reflected the man’s view of his pastor not being able to see how important his own life’s purpose was.