Skin biopsy: symptoms, causes and treatment

A skin biopsy is a medical procedure where a doctor removes a small sample of skin tissue for examination. This patch of skin, often no larger than a few millimetres, is then sent to a laboratory where a pathologist looks at it under the microscope. A pathologist is a doctor who specializes in examining cells and tissues to detect and diagnose diseases.

The word biopsy comes from the Greek and literally means “seeing life”. The pathologist assesses the structure of the skin cells, the presence of inflammatory cells, and signs of abnormal cell growth. This microscopic examination provides information that is often not visible to the naked eye, even to an experienced dermatologist.

A skin biopsy is usually performed at your doctor's office or a dermatologist under local anaesthesia. So you don't feel any pain while removing the tissue. This procedure usually takes just a few minutes, although waiting for results from the lab can take one to two weeks.

There are various reasons why a doctor may want to do a skin biopsy. Sometimes there is doubt about the diagnosis and the doctor wants more certainty before starting a treatment. In other cases, a skin condition does not respond to the usual treatment. When skin cancer is suspected, a biopsy is essential to determine whether a tumour is benign or malignant.

A skin biopsy is not a treatment but a diagnostic tool. The goal is to gather information that helps make the correct diagnosis. The results come in the form of a pathology report that describes what the pathologist saw. Based on this report, your doctor can make a definitive diagnosis and develop a treatment plan.

A skin biopsy is not done for every skin condition. Physicians use this procedure only when it is necessary for diagnosis or treatment. There are three main situations where a skin biopsy is considered.

The first situation is when the doctor wants to have a clinical diagnosis confirmed. A clinical diagnosis is based on what the doctor sees and what you tell about your symptoms. In some skin conditions, the appearance is so characteristic that the doctor is fairly certain, but still wants certainty before starting a treatment. This mainly occurs in conditions that require long-term or intensive treatment.

An example is a suspicion of a specific form of eczema that does not respond to conventional treatments. The doctor can then do a biopsy to see if it is indeed that type of eczema, or if there is another skin condition that requires different treatment.

The second important reason is to examine a skin tumor to determine if it is malignant. If you have a spot, bump, or injury that looks suspicious, the doctor wants to know if it's skin cancer. The distinction between benign and malignant tumors is crucial because it determines what treatment is needed and how urgently it needs to be done.

If skin cancer such as basocellular carcinoma, squamous cell carcinoma or melanoma is suspected, a biopsy or excision is the only way to get certainty. Appearance alone is not sufficient to make this diagnosis. Only by looking at the tissue under a microscope can the pathologist see whether cancer cells are present, what type they are and how deep the tumour has penetrated the skin.

The third situation is when a skin injury does not respond to the treatment that should normally work. If you've been using a cream or ointment for weeks or months without improvement, this may mean that the diagnosis is wrong. A biopsy then helps to find out what is really going on. Perhaps there is another condition that looks the same, or there have been complications such as an infection or an allergic reaction to the treatment itself.

A skin biopsy can be performed in various ways. The choice depends on the size and nature of the injury, and what exactly the doctor wants to investigate. There are two main techniques that are most commonly used: the common skin biopsy and the punch biopsy.

In a normal skin biopsy, the doctor cuts out an oval-shaped piece of skin around the skin disorder. This technique is mainly used when the entire injury has to be removed, for example in the case of small tumors. When the entire injury is excised, you usually no longer speak of a biopsy but of an excision. The doctor uses a scalpel to cut the skin and removes the tissue including a small margin of healthy skin around it. This margin is important because the pathologist can then also see the transition from healthy to affected tissue.

The size of the margin depends on what the doctor suspects. In the case of an innocent skin defect, he usually cuts 1 to 2 millimeters next to the injury. If a malignant tumor is suspected, he takes a wider margin of approximately 3 to 5 millimeters. After removing the tissue, the doctor stitches the wound edges together with small stitches for a neater healing result.

A punch biopsy is another technique where the doctor pricks out a small, round patch of skin with a special instrument that looks like a tiny drill. This instrument has a hollow cylinder shape with sharp edges and comes in various sizes, usually between 3 and 6 millimeters in diameter. The doctor presses the instrument into the skin and rotates it, cutting out a cylinder of skin.

The advantage of a punch biopsy is that it is quick and usually does not require stitches. In the case of small punch biopsies, the doctor may suffice with a pressure bandage and the wound will heal on its own. Larger punch biopsies may require one or two stitches. This technique is often used for rashes that are spread over a larger area, where you want to take a sample in different places.

For both techniques, the procedure is done under local anaesthesia. The doctor first injects an anesthetic into the skin around the area he wants to examine. This injection stings briefly, but after that you won't feel the procedure itself. The narcotic effect lasts for several hours.

After the biopsy, the doctor applies a bandage to the wound. He gives instructions on how to care for the wound: you should usually keep the area dry for the first 24 to 48 hours and then clean it gently. If sutures have been placed, they should be removed after about a week, depending on the location.

The removed tissue is placed in a special storage solution and sent to the laboratory. There, the tissue is processed, cut into very thin slices and placed on a glass. These slices are colored with special dyes that make different structures in the tissue visible. The pathologist looks at these specimens under the microscope and writes a report with his findings.

Skin biopsies can be performed anywhere on the body, depending on where the suspected skin disorder is located. There is no location on the skin where a biopsy cannot be done, but certain areas do require extra care.

Facial biopsies are often performed because it is a common site for skin cancer due to sun exposure. The nose, cheeks, forehead, and ears are common locations. In facial biopsies, the doctor pays extra attention to the cosmetic result and tries to make the incision in the direction of the natural skin lines so that the scar is less noticeable later.

The torso is another common location for biopsies. Suspicious birthmarks, rashes, or abnormalities on the chest, abdomen, back, or shoulders may be a reason for a biopsy. These locations are often easier to treat than the face. Biopsies are performed on the arms and legs for rashes, birthmarks, or other lesions. The hands and feet are more difficult because the skin there is tense and wounds are harder to heal due to constant movement and pressure.

Care after a skin biopsy is important for good healing and to prevent complications. Although it is a minor procedure, it remains a wound that needs attention.

Immediately after the biopsy, you will have a bandage on the wound. Keep this bandage dry for the first 24 hours. This means that you have to take a shower carefully and not wet the area. Protect the bandage with plastic film or waterproof bandage. After 24 hours, the wound may become wet, but then pat it dry carefully.

In the first few days, you may feel some pain when the anaesthetic wears off. This pain is normally mild and can be relieved with common pain relievers. If the pain is severe or increases instead of decreasing, this may indicate a complication such as an infection. Then contact your doctor.

Bleeding is rare after a skin biopsy, but it depends on the patient's location and history. Bleeding may occur when using blood thinners or facial biopsies. The chance is greatest when the anaesthetic has just worn off. Slight blood spots in the bandage are normal, but if bright red blood seeps through, press the wound firmly with a clean cloth for 10 minutes.

The wound heals in stages. The first week, a crust forms that protects the wound. Don't touch or pry on this crust. The crust falls off on its own when the skin underneath has healed. If you have stitches, go back to the practice after about a week to have them removed. Suture removal is quick and almost painless.

A scar usually remains after a biopsy. The size depends on how big the biopsy was and where it was done. Facial scars are often smaller and less noticeable because the skin heals well there. In the first months, the scar is red or pink, but it gradually fades. After a year, it is usually white and much less noticeable.

To help scars heal as beautifully as possible, you can protect the area from the sun during the first year. Sunlight can darken scars. Use high-factor sunscreen or cover the area with clothing.

Infections are rare after a skin biopsy because the procedure takes place under sterile conditions. Signs of infection include increasing redness around the wound, warmth, swelling, pus, or fever. If you see these symptoms, contact your doctor right away. An infection can usually be treated well with antibiotics.

There are several things that people sometimes do that don't help the healing process and can sometimes even cause harm.

Picking at the crust is a common mistake. The crust protects the new skin that grows underneath. If you remove the crust before the skin underneath is ready, you create another wound that needs to heal again. This not only extends the healing time, but also increases the risk of infections and uglier scars.

Too much water and soap on the fresh wound can be harmful. In the first days, you should keep the wound dry. You should also avoid excessive washing later. Too much soap dries out the wound and can cause irritation. Rinsing with clean water is sufficient.

Homemade ointments and creams that are not prescribed by your doctor can cause problems. Products such as honey, tea tree oil, or aloe vera may cause irritation or allergic reactions. Only use products recommended by your doctor.

Intense physical activity shortly after the biopsy can strain the wound, especially if it's in an area that moves a lot. This can cause the wound to reopen or the stitches to peel off. Therefore, avoid strenuous exercise the first week after the biopsy. Ordinary walking and light activities are usually fine.

Smoking significantly slows wound healing. Nicotine constricts the blood vessels, causing less oxygen and nutrients to go to the wound. If you smoke, try to quit or at least cut back while your wound heals.

Tight clothing over the biopsy may rub and cause irritation. Opt for loose clothing that does not touch the wound. For biopsies in folds or under clothing, use gauze to protect the wound from friction.

Does a skin biopsy hurt?

The biopsy itself doesn't hurt because you're getting local anesthesia. You can feel the sting of the narcotic injection, which can be short. Afterwards, you may feel some pain that is similar to an abrasion. This pain is usually mild and tolerable with common pain relievers.

How long will it take before I get the results?

It usually takes one to two weeks for the pathologist to examine the tissue and write a report. This time is necessary because the tissue must be processed first, which takes several days. In complex cases, the pathologist can do additional examinations or seek the advice of a colleague, which can extend the time to three weeks.

Is there always a scar left behind?

Yes, a scar is unavoidable during a skin biopsy because tissue has been removed. Size and visibility depend on several factors: how big the biopsy was, where on your body it was done, and how well your skin is healing. After one year, the scar is usually much lighter and less noticeable.

Can I go home immediately after a biopsy?

Yes, a skin biopsy is an outpatient procedure. This means that you can go home immediately after the procedure. There is no need for a recovery period where you have to stay. Most people resume their normal activities immediately, with the exception of strenuous physical exercise.

What if the biopsy shows it's cancer?

If the pathologist finds skin cancer, your doctor will discuss the results with you and explain what this means. Most forms of skin cancer are treatable, especially when detected early. Your doctor is likely to refer you to a dermatologist or surgeon who specializes in treating skin cancer.

Do I have to stop taking blood thinners before a biopsy?

This depends on the type of blood thinner you're taking and why you're taking it. Always discuss this with your doctor beforehand. Some blood thinners are safe to continue; others require you to stop temporarily. Your doctor weighs the risk of bleeding during the biopsy against the risk of stopping the blood thinner.

1. Skindr dermatologists
2. Health and Science: Skin Biopsy
3. eBPNet (Evidence-Based Practice Network)
4. Dutch Society for Dermatology and Venereology