Skin biopsy: What is it and what does it involve

What is a skin biopsy?

A skin biopsy is a minor surgical procedure to remove a sample of skin affected by disease. The sample is then sent away for analysis by a pathologist, who examines the skin in cross section under a microscope and diagnoses the disease seen.

Why are skin biopsies needed?

Some diseases affecting the skin have characteristic features that can be diagnosed without performing diagnostic tests. For others, basic tests performed during the consultation can be sufficient for a diagnosis to be made. However, some skin diseases are not so characteristic, and when the disease is affecting the deeper parts of the skin, biopsies are required in order to establish a diagnosis. Very rare skin diseases or diseases presenting in a similar way to other conditions, may also require biopsies in order to gain a diagnosis.

How are skin biopsies taken?

Skin biopsies are often taken using biopsy punches. These instruments remove a circle of skin affected by disease, and range from 4mm in diameter to 8 mm in diameter. It is usually only necessary to place one stitch in the hole created by the biopsy punch.

A punch biopsy site with one stitch present

Sometimes with larger skin lesions, or when skin disease causes lesions such as blistering, biopsies are performed by removing an ellipse of skin with a scalpel blade. This type of skin biopsy sometimes requires a few stitches to close the biopsy site. For the vast majority of cases, at least 3 biopsies are taken irrespective of the technique used. The selection of the biopsy sites is crucial to maximise the chances of obtaining the correct diagnosis, so a very detailed examination of the skin is needed prior to the procedure.

Skin biopsies can usually be performed under light sedation and local anaesthesia in dogs and cats. This means that biopsies can be taken quickly with the animal returning home usually within an hour or two. When skin disease affects more sensitive areas of the body such as the face and feet, a general anaesthetic is usually required. However, the procedure to obtain the biopsies is still a relatively quick process, so the anaesthetic time is often short.

How long will it take to get the results?

The sections of skin are sent to an external laboratory, where they are processed ready for the pathologist to examine. A full report back from the laboratory normally takes around 5-7 days.

A section of skin shown in cross section following removal by biopsy

Is there any aftercare?

As performing a skin biopsy is a minor surgical procedure, – there is normally very little aftercare. Drugs such as antibiotics and pain killers are not usually required. Depending on the sites affected and the stitch material used, it may be necessary to remove the stitches after around 10 days.

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