A punch biopsy involves using a special instrument to cut out a cylinder-shaped piece of skin. This procedure leaves a small hole in the skin that is then closed with stitches. It leaves a scar that is either a line or football-shaped. Punch biopsies can remove the entire depth of a mole, but they are difficult to use in certain locations, such as where bone is close to the skin (e.g., on a knuckle or elbow). In order for a punch biopsy to be performed, the mole must be small enough to fit in the punch biopsy instrument. Some moles are too big to be completely removed by the punch biopsy method. These moles may be only partially sampled, removed by a shave biopsy, or surgically excised.
In a shave/scoop biopsy, a health-care provider cuts off a small spoon-shaped piece of skin using a scalpel or blade. The resulting wound is not closed with stitches, and has a tendency to leave a chickenpox-like scar. Shave biopsies may not remove the full depth of a mole, but are frequently used when the growth is greater than 4-5 mm in diameter.
An excisional biopsy may be performed if the mole is large or if the results of your punch or shave biopsy show suspicious precancerous or cancerous cells. In this kind of biopsy, the entire width and depth of the suspicious area is removed, along with a small amount of tissue from all sides. These “margins” are removed to make sure that no suspicious cells remain. The wound is closed with stitches, and the amount of scarring depends on the size and location of the incision.