A biopsy is the removal of a piece of skin to help render a diagnosis of skin cancers or inflammatory conditions. Dermatologists biopsy an area to confirm a diagnosis that cannot be rendered with the eyes alone. We need a microscope to be certain. 

If a patient comes in with a mole, the dermatologist can closely examine the mole and suspect it may be skin cancer or a spot that could later become a cancer – but without a biopsy, we can’t know for sure. So, we remove the growth to determine the most accurate diagnosis. 

Another patient might present a rash. Is it eczema, psoriasis, an autoimmune disease, or bedbug bites? If it’s not obvious based on history and visual inspection alone, the dermatologist will biopsy the area to determine the diagnosis. 

Dermatologists biopsy in one of two ways, depending on the area. To determine the depth of the spot and which procedure is best, we first examine suspect places under a dermatoscope (a handheld dermatological microscope).  

For relatively superficial spots, where the answer lies near the surface of the skin…

Skin biopsy procedures include removing a small portion or the entire skin lesion. Using a razor blade, we shave off a thin piece of skin (about 1-3 mm in depth) for further examination. The width of the removed area can vary, but overall this biopsy heals quickly with minimal scarring. 

For other suspect moles or rashes…

We need to go deeper to accurately diagnose. In these cases, we use a different device (called a trephine) that allows us to remove a plug of skin up to one centimeter in depth. This allows us to examine the issues that may exist deeper in the skin (in the blood vessels or fat) that we cannot see by doing a surface scrape.

When is a Biopsy Needed? 

If we suspect cancer or if you have a rash that could look like more than one condition, you often need the biopsy to get the right answer. We biopsy moles, freckles, spots, or rashes when they fall into one of two categories — potential cancer or inflammatory conditions.

Skin cancer is one of the main reasons dermatologist biopsy patients. If a spot or mole looks suspicious, we’ll conduct a biopsy for more information. 

Moles can be normal or suspicious of melanoma — one of the most dangerous forms of skin cancer. If a dermatologist identifies a mole as “suspicious,” we will biopsy it to determine if it is malignant.

Other spots can indicate skin cancers such as basal cell carcinoma or squamous cell carcinoma. These sun-induced skin cancers generally do not look like moles or freckles, but have their own unique appearance. Although not as dangerous as melanoma, we need to find, diagnose, and treat them as early as possible. 

Even when a dermatologist is relatively certain a spot is cancerous based on clinical observation, we will conduct a biopsy to identify the exact subtype of the cancer. Basal cell carcinoma, for example, has over a dozen subtypes — each with specific treatments proven to be most effective for that exact type. Knowing the subtype helps dermatologists plan the best course of treatment — whether the spot needs to be scraped, treated with a cream, or surgically removed.

We also biopsy rashes to accurately diagnose inflammatory conditions. Rashes can fit a variety of inflammatory conditions — each with different treatments. A biopsy allows us to identify the exact condition so we can treat it effectively. 

Occasionally, we conduct biopsies on potentially infected tissue. If we suspect an infection that requires a specific treatment, a dermatologist can biopsy the area and send it to the lab for a specific diagnosis. 

Is There An Alternative to a Biopsy?

Biopsies are the only way to receive an accurate diagnosis of moles or suspicious spots. Overall, biopsies are safe procedures with minimal risks, and virtually no scarring. They cause minimal discomfort, heal within a matter of days, and provide diagnostic information that cannot be obtained any other way.

A dermatologist can suspect conditions based on what we visually observe and the patient’s history, but without a biopsy, we cannot always make an actual diagnosis. 

What Should You Expect During A Biopsy?

Skin biopsy procedures begin with the exam. Before we begin, we always verify the patient name and have the patient sign a consent for biopsy, making sure they understand it will involve an injection of anesthetic, a removal of a piece of skin, a bandage, and instructions for care. They can expect their rash or mole biopsy results within a week. 

Then, we begin the exam using a sharpie to mark any spots we need to biopsy. Marking the spots during the exam saves time and improves accuracy. Patients who have battled melanoma may have many spots — but not all are suspicious. We mark the spots with a sharpie as we go so we can more easily catalog and locate them at the end of the examination. It’s not uncommon for patients who have previously had skin cancer or are at high-risk for other reasons to have more than one biopsy at a time. 

These markings also help ensure we biopsy the right area. If you anesthetize a spot without marking it, it can be hard to locate later. The epinephrine can blanch out a red spot, causing it to temporarily disappear. Marking the spots prior to administering these medications allows us to biopsy the right place without later having to repeat the effort. 

When it’s time to biopsy, we clean the marked area with an antiseptic such as alcohol, iodine, or chlorhexidine. We then inject a small amount of anesthetic into the skin and administer a small amount of epinephrine to minimize bleeding. Once these medications have taken effect, we biopsy the spot with one of two distinct devices (depending on the depth at which we need to penetrate in order to get the answer). 

For the vast majority of biopsies, no suture is needed. 

After a shave biopsy, we apply a styptic solution to stop residual bleeding. Then we apply petroleum jelly and a bandage and give the patient instructions for caring for their biopsied area.

For deeper biopsies, we put a tiny plug into the removed area. This chemical clotting factor plug looks like styrofoam and helps stop the bleeding. We then apply a slightly more elaborate pressure dressing. Only punch biopsies broader than three millimeters in require a stitch. For any biopsy with a diameter less than that, the eventual cosmetic results are the same with or without stitches. And if a patient doesn’t need a stitch, they won’t have to come back for stitch removal — making the biopsy a more convenient process. 

Once the biopsy is taken, we place the specimen into a small, plastic jar containing formaldehyde. This preserves the specimen until it can be analyzed and evaluated. A label is immediately placed on the jar, usually in the presence of the patient to avoid error, and the specimen is logged into the computer. 

Specimens are then sent overnight to a laboratory to be processed. At the lab, each specimen is embedded into wax and sliced vertically. These specimens are then stained with chemicals that make it easier to visualize different parts of the tissue and processed into a slide (or series of slides). 

A board-certified dermatopathologist examines each slide under a microscope and renders a diagnosis or gives a set of potential diagnoses that are consistent with what we observe. This report is then sent back to the dermatologist who conducted the biopsy. The dermatologist contacts the patient with their rash or mole biopsy results within a week of the initial biopsy.

Biopsy FAQ’s

Is there scarring or pain? 

There is minimal pain with the anesthesia injection. It’s a very thin needle and it only takes a second to inject the right amount of anesthesia. 

If the patient is afraid or if we’re taking care of a young child, we take extra measures to ensure their comfort. We apply an anesthetic cream under a bandage for 20 minutes prior to the procedure or distract them with a cold spray or a vibrating device to make the injection almost unnoticeable. But even for adults with the standard approach, pain is minimal. 

There is little to no scarring with this procedure. Biopsied areas should heal within a matter of days. 

Is my insurance going to cover this? 

Yes, most insurance companies cover skin biopsy procedures. Your exact out-of-pocket expense depends on your insurance plan and if you’ve met your deductible, but it will be covered.

Biopsies are medically-justifiable (not cosmetic) procedures. If we’re doing a biopsy, it’s because we need information to render a diagnosis — we need to rule out a form of cancer or verify an inflammatory condition so we can treat it with the right medication. It is medically necessary when we do not have enough information to make a diagnosis on visual observation alone. 

Will my biopsy get infected? 

Biopsies have a very low rate of infection. There’s usually no need for ointments like Neosporin. We recommend patients use basic petroleum jelly and a bandaid until the wound has healed completely.

When will I get the results, and will I have to come back? 

We call you with your inflammation, spot, or mole biopsy results almost always within a week of your biopsy. Those results then determine your next steps. If the biopsy was for a rash, we’re often able to prescribe a cream or pill for treatment and the patient will usually not have to come back into the office. 

In other situations, patients may need to come back in to discuss more complicated treatment options or have the spot surgically removed. 

Will the answer be definitive? 

Generally, yes. 

In the case of a rash, the answer is usually a straightforward diagnosis. 

There is the potential for outliers that are difficult for the pathologist to diagnose with 100% certainty. Occasionally a challenging mole can pose difficulty for the pathologist. We may not be able to tell if a spot is an early melanoma or not. In these cases, we treat it as such to be safe. 

Occasionally we get a suggestion, list, or a non-diagnostic report that asks for another biopsy. Some pathologist reports are descriptive. They may describe the types of cells and the changes, then list several potential diagnoses. 

We cannot tell patients with 100% certainty that we’ll get a definitive answer from their biopsy, but we usually do.

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