American Melanoma Institute · 5 min read
How shave, punch, incisional, and excisional skin biopsies are done, why a doctor picks one, and what healing and results look like.
A skin biopsy removes a small piece of skin so a pathologist can examine it under a microscope. For most suspicious spots, no scan or blood test can replace that look at the cells. The procedure happens in the office and usually takes a few minutes.
The doctor cleans the skin and injects a local anesthetic with a very fine needle. The injection stings for a few seconds. After that you may feel pressure or tugging, and you shouldn't feel sharp pain.
Before starting, doctors want to know about blood thinners, bleeding problems, drug allergies, and pregnancy. If needles make you lightheaded, the staff can have you lie down.
In a shave biopsy, the doctor slides a small blade across the skin and lifts off the spot along with the top layers under it. The shallow wound heals on its own without stitches, usually within 1 to 3 weeks.
Doctors often choose a shave for raised spots and for suspected basal cell or squamous cell cancers. The main drawback is depth. A shallow shave can cut through the bottom of a growth, and then the pathologist can't tell how deep it went.
Saucerization, also called a deep shave or scoop biopsy, solves part of that problem. The blade is angled down into the dermis, the thicker layer under the surface, so the whole spot comes out in one dish-shaped piece. The American Cancer Society notes that when a deep shave is used on a possible melanoma, the blade needs to pass below the suspicious area so its thickness can be measured.
A punch tool looks like a tiny round cookie cutter. Most are 3 or 4 mm wide, within a range of about 2 to 6 mm. The doctor rotates it down through every layer of the skin, lifts out a small core, and usually closes the hole with 1 or 2 stitches.
A punch gives the pathologist a full-thickness sample, which helps with rashes and with growths that sit deep in the skin. The limit of a punch is width. A 4 mm punch taken from a 12 mm mole shows only part of that mole, and the part left behind could hold the most abnormal cells.
Both of these use a scalpel, go through the full thickness of the skin, and end with stitches. An incisional biopsy removes a portion of a growth. Doctors use it when a spot is large or sits where removing all of it at once would be hard, such as the face, a palm, or the sole of a foot.
An excisional biopsy removes the entire spot with a thin rim of normal skin around it. For a suspected melanoma, guidelines prefer this approach when it's practical. The American Academy of Dermatology guidelines of care describe a narrow excisional biopsy with 1 to 3 mm margins that takes in the full width of the lesion.
The reason is measurement. Melanoma treatment depends on how thick the tumor is at its deepest point, and the pathologist can only measure that with confidence when the whole lesion is on the slide. The margins stay narrow on purpose, because the wider surgery that treats a melanoma is planned after the thickness is known.
The office will send you home with a bandage and written instructions. General advice is to keep the area clean and avoid bumping or stretching the skin nearby. Stitches come out in about 3 to 14 days, sooner on the face and later on the back and legs.
A little oozing on the first day is common. Firm, steady pressure for 10 minutes stops most bleeding, and bleeding that continues after that deserves a call to the office. Infection affects roughly 1% to 5% of excisional biopsies and is rare after a small punch. Spreading redness, pus, fever, or pain that grows after the second day are the signs offices want to hear about.
Every biopsy leaves a mark. A shave usually heals as a flat, round patch that may stay lighter or pinker than the skin around it. Punch and excision sites heal as a short line.
The chest and shoulders tend to form thicker scars than other sites. People with darker skin have a higher chance of raised scars. If you've had a keloid or a thick scar before, mention it, because it can change where and how the doctor takes the sample.
Most results come back in about 1 to 2 weeks. Special stains, molecular tests, or a second pathologist's review add time, and a longer wait doesn't mean the news is bad.
You can request a copy of the pathology report for your own records. If a mole that was shaved off grows back, the American Academy of Dermatology advises having it looked at again, and the earlier report gives the dermatologist a baseline to compare against.
