A skin biopsy is the removal of a small sample of skin so it can be examined under a microscope. It is arranged when appearance alone cannot settle a question, and it is a routine step rather than a conclusion about what anything is.
Why is a sample taken at all?
Because appearance has limits, and clinicians know exactly where those limits are.
A great deal of dermatology is settled by looking, with good light and a dermatoscope. Some questions are not, either because two quite different processes can look similar at the surface or because what matters is happening below it, out of reach of any amount of careful examination from above. A biopsy answers what looking left open.
Hearing that a biopsy is proposed is unsettling. The framing worth holding onto is that it is a step towards an answer rather than an answer already arrived at. A biopsy is taken for inflammatory conditions, for infections that have not behaved as expected, and for unclear rashes, not only for pigmented lesions.
What are the techniques?
Several, and which one is used depends on what question is being asked.
A punch biopsy uses a small circular instrument to take a core of skin through the full thickness, which suits conditions where the relationship between layers matters. A shave biopsy removes a raised area at or near the surface. An incisional biopsy takes a portion of a larger area. An excisional one removes something in its entirety.
The choice is clinical and it follows from the question being asked. A sample intended to characterise an inflammatory process needs depth; one intended to remove something entirely needs margins, and no single technique does both jobs well. It is worth asking which is planned and why, since the answer explains a good deal about what the clinician is thinking.
What is the appointment like?
Shorter and less dramatic than the anticipation suggests, which is a recurring theme in dermatology.
The area is cleaned and local anaesthetic is injected, and that injection is the part most people notice. Once it has taken effect the sensation is pressure rather than pain. The sample is taken, the area is closed if it needs closing, and a dressing goes on. That is the whole of it.
Stitches are used for some techniques and not others. Where they are, you will be told whether they dissolve or need removing, and when to come back if they do.
Aftercare instructions come from the clinic and they are specific to what was done and where. This page deliberately gives none, because wound care depends on the technique, the site and you.
What happens to the sample?
It goes to a laboratory. There it is processed, sectioned, stained and examined under a microscope by a pathologist, and every one of those steps takes time, which is the main reason a result is not available on the day and cannot be hurried by asking.
The pathologist produces a report describing what the tissue shows, and it returns to the clinician who took the sample. Interpretation happens there: the report describes the tissue, and the clinician relates it to you, your history and what they saw.
Occasionally a sample is inconclusive, or the report raises a further question, and a second sample is needed. That is a recognised outcome rather than a failure of the first one.
What is worth asking?
Ask which biopsy technique is planned and why that one. The reasoning tells you what question is being answered.
Enquire about the mark to expect, particularly on a visible area. The answer sometimes changes where a biopsy is taken from, and it is far better discussed beforehand.
Ask when the result is expected, who will contact you, and what to do if nobody does. This is the point where people most often fall through a gap, and closing it takes one sentence.
Ask what the biopsy result will change. Knowing in advance whether an answer leads to a decision, or simply confirms a description, makes the wait a great deal easier to hold.
What this page does not do
It gives no aftercare instructions, no wound care routine, no timescales and no interpretation of any result. All of that comes from the service performing the procedure, which knows what was done and where.
Common questions
Does a biopsy mean cancer is suspected?
No. A biopsy is arranged whenever looking cannot settle a question, and that covers inflammatory conditions, infections and unclear rashes as well as pigmented lesions. It reflects the limits of examining by eye rather than a conclusion already reached.
Is a skin biopsy painful?
Local anaesthetic is used, so the procedure itself is usually described as pressure rather than pain. The injection of the anaesthetic is the part people notice. Afterwards the area is generally sore for a short period, and the clinic will explain what to expect.
Will it leave a mark?
Some mark is usual, and how noticeable it is depends on the technique, the site and how your skin heals. This is a reasonable thing to ask about beforehand, particularly for a visible area, and the answer may influence where a sample is taken from.
How long do results take?
Longer than most people expect, because tissue has to be processed before it can be examined. The interval varies by service, and asking at the time is worth doing, along with establishing who will contact you and what happens if nobody does.
Who examines the sample?
A pathologist, working with a microscope, who produces a report that goes back to the clinician who took the sample. The report is what turns a description of appearance into a definite answer, which is the entire reason the sample was taken.
Sources
- Biopsy — NHS (United Kingdom) · accessed
- Patient information on skin conditions and treatments — British Association of Dermatologists (United Kingdom) · accessed
Last updated . How this page was written.