DermNet NZ

Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Skin biopsy

A skin biopsy is when your dermatologist removes a piece of skin and sends it to a pathology laboratory where a histopathologist looks at it under the microscope.

Why do you need to have a skin biopsy?

Skin biopsies are performed to help with the diagnosis of your skin condition. Sometimes, different skin conditions can look similar to the naked eye so additional information is required. This is obtained by looking at the structure of the skin under the microscope after the cells have been stained with special coloured dyes.

There are two situations in which this usually occurs:

What is involved in having a skin biopsy?

Your dermatologist will explain to you why the skin biopsy is needed and the particular procedure involved.

Shortly before the skin biopsy, you will be given a small injection of local anaesthetic to make the area numb. This usually stings momentarily but the skin quickly becomes numb.

The dermatologist will perform the skin biopsy. You may feel a pushing sensation in the area where the skin biopsy is being performed but there should not be any pain. You should tell the doctor if the procedure is painful during the biopsy.

You may have stitches depending on the type of skin biopsy. Your dermatologist will tell you when to get them removed.

A dressing will usually be applied to the site of the biopsy. This should be left in place for the first 24 hours. After that you can remove the dressing.

Your dermatologist will arrange to tell you the result of the biopsy. It usually takes about one week for the doctor to obtain the result from the pathology laboratory, but can sometimes take longer if special stains are required. There will be a small scar left after the skin biopsy site has healed.

Punch biopsy

Punch biopsies are quick, convenient and usually only produce a small wound. They allow the pathologist to get a full thickness view of the skin. More than one punch biopsy may be required depending on the condition being investigated.

The punch biopsy blade takes a small round core of tissue ranging from 2mm-6mm in diameter although 3-4mm is the usual size.

Sometimes a stitch will be required or, if the wound is small, it may heal adequately without a stitch.

Shave biopsy

A shave biopsy may be used if the skin lesion is suspected to only affect the top layers of the skin (epidermis and dermis)

The dermatologist will take a very superficial slice of skin from the area affected with a scalpel, Dermablade or razor blade. There are usually no stitches required after a shave biopsy, but there will be a small scab that should heal in 1-2 weeks depending on the skin lesion involved.

Scoop biopsy

A scoop biopsy is used to remove a skin lesion in its entirity by "scooping" it out. It is a deep form of shave biopsy.

A scoop biopsy is used to rapidly remove lesions with low suspicion of malignancy, for example, an odd-looking flat mole that is unlikely to be melanoma. There are usually no stitches required after a scoop biopsy, but it takes longer to heal than a superfiical shave biopsy and leaves a scar.

Incisional biopsy

Incisional biopsies are used when a larger piece of skin is needed to make a correct diagnosis. The dermatologist will cut out a piece of skin with a scalpel blade. Stitches are usually required after an incisional biopsy.

Complications of skin biopsy

Skin biopsy is straightforward, minor surgery, so complications are uncommon. But occasionally, the following may arise.

Related information

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Author: Dr Sonya Havill MBChB FRACP, Registrar, Department of Dermatology, Waikato Hospital, Hamilton, New Zealand.

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If you have any concerns with your skin or its treatment, see a dermatologist for advice.