Skin biopsy (punch method)
A punch skin biopsy is a short procedure to remove a small piece of skin for examination under a microscope or to grow cells. These cells can be tested for abnormalities of the DNA or to show whether a specific chemical reaction can or cannot take place.This page explains about a skin biopsy (punch method) and what to expect when your child comes to Great Ormond Street Hospital (GOSH) to have this procedure.
A punch skin biopsy is usually carried out to determine or confirm a diagnosis. There are also certain metabolic or chromosome disorders that can only be diagnosed by a skin biopsy. The reason for your child’s biopsy will be discussed with you fully by your child’s doctors.
Your child will usually have a skin biopsy as a day case on the ward. This means your child will arrive at the hospital, have the procedure and go home on the same day, unless further investigations or treatment are needed. If your child is having another procedure under a general anaesthetic or sedation, the biopsy may be done at the same time.
What happens before the biopsy?
The nurse caring for your child will see you when you arrive on the ward to explain the procedure in more detail, discuss any questions or concerns you may have and ask you to give your permission for the procedure by signing a consent form. If your child has any medical problems, for instance, allergies, please tell the nurse about these.
What does the procedure involve?
Skin biopsies are usually done while the child is fully awake, although the area of skin where the biopsy is taken will be numbed. If your child is worried by the procedure you can help by reading a story, playing a game or singing a song. More information about distraction therapy is available in our leaflet. Depending on the area being biopsied, a young child may be able to sit on your lap during the procedure.
The biopsy takes about a minute. The biopsy site is numbed using a cream or spray before a local anaesthetic is injected. Once the area is completely numb, the nurse or doctor will clean it with an antiseptic wipe. The punch skin biopsy instrument is gently inserted into your child’s skin, rotated and a small circle of skin is carefully removed.
The sample of skin will be sent to the laboratories for examination under a microscope and/or to grow cells. The biopsy site usually bleeds slightly straight after the procedure, but this will stop when pressure is applied to the site. The area will be held closed by Steri-Strips®, which are like strong sticky plasters, and then covered with a dressing.
There is a very small chance that the biopsy site could become infected afterwards. A child with known immune problems may be given an antibiotic cream to put on the area after the dressings and Steri-Strips® have been removed. There is a chance that a scar, similar to a chicken pox scar, may form. This is more likely if your child has scarred easily in the past.
When your child goes home
The biopsy site may feel uncomfortable for a day or two. Your child may need paracetamol given according to the instructions on the bottle, unless you have been advised otherwise. You should remove any pressure dressing after 24 hours, but leave the dressing underneath in place. After 48 hours, you can remove the rest of the dressing.
The Steri-Strips® may fall off of their own accord – otherwise they can be soaked off in the bath or shower three days after the biopsy. Your child can go back to nursery or school the day after the biopsy.
How long will it take to get the test results?
The results of the test will be available within several days if it is just necessary to look at the skin under a microscope. Results of biochemical testing may be available within six to eight weeks. However, some of the more specialised biochemical tests have to be sent away to a specialised laboratory and so can take up to six months to come back. Analysis of the genes responsible for a disease (carried on the DNA) can also take several months.
You should call your GP or the ward
- If the biopsy site is still painful more than three days after the biopsy was taken and normal pain relief does not help
- If the biopsy site is red or ‘angry’-looking;
- If your child develops a high temperature, and is not eating.