What is a Skin Biopsy?
A Skin Biopsy is a short procedure in which a healthcare professional removes a small piece of abnormal skin for laboratory examination. A pathologist studies the tissue under a microscope to help identify the cause of a rash, sore, growth, colour change, or other skin problem.
It can help in diagnosing conditions such as psoriasis, eczema, bacterial or fungal infections, autoimmune skin disorders, and skin cancer. It is recommended in cases where a physical examination alone cannot provide a definitive diagnosis or when a suspicious lesion needs to be further assessed.
But being told you need a biopsy doesn’t mean that cancer has been found. The purpose is to replace uncertainty with a tissue-based diagnosis.
Why Does the Type of Skin Biopsy Matter?
The skin is made up of several layers. Different conditions affect different depths. For that reason, the clinician chooses a biopsy method based on the appearance, location, size, and suspected cause of the abnormal area.
Shave Biopsy
A shave biopsy removes tissue from the upper layers of the skin. It may be suitable for raised or superficial lesions.
Punch Biopsy
A circular instrument removes a small core containing deeper layers of skin. A punch biopsy can be useful for inflammatory rashes, some infections, and lesions where the depth and arrangement of the tissue matter.
Incisional Biopsy
Only part of a larger lesion is removed. This method may be chosen when sampling the most representative area is more appropriate than removing the whole lesion.
Excisional Biopsy
The entire lesion is removed, sometimes with a small margin of surrounding skin. This may be preferred for certain suspicious moles or growths where examining the full lesion provides important diagnostic information.
The smallest procedure is not always the most informative one. A sample must be deep and wide enough to answer the clinical question.
What are the Symptoms that Prompt this Test?
Your healthcare provider may recommend a Skin Biopsy if you have:
- A new or changing mole
- A persistent skin rash
- A skin lesion that does not heal
- Unexplained skin discolouration
- Persistent itching
- Scaly or rough patches of skin
- A bleeding or ulcerated skin lesion
- Unusual skin growth or lumps
- Skin thickening
- Chronic inflammation of the skin
- Persistent blistering
- A suspected bacterial, fungal, or other infection
- Possible psoriasis, vasculitis, lupus, or another inflammatory or autoimmune condition
- A lesion that may represent melanoma, basal cell carcinoma, or squamous cell carcinoma
Many skin conditions resemble one another when viewed from the outside. A biopsy allows the laboratory to examine the pattern within the tissue, which can help distinguish between conditions that require very different management
How is the Test Performed?
Preparation
- Inform your healthcare provider about any medications you are taking, especially blood thinners.
- Tell your healthcare provider about any allergies, particularly to local anesthetics or antiseptic solutions.
- Follow instructions regarding medication adjustments if advised before the procedure.
- Follow any additional preparation instructions provided by your healthcare provider.
Collection
The procedure depends on the type of biopsy.
- The skin area is cleaned using an antiseptic solution.
- A local anaesthetic is used to numb the area.
- The required skin sample is obtained using a specialised instrument such as a biopsy punch, razor or scalpel.
- The specimen is placed in a container with preservative and sent to the laboratory.
- Larger biopsies may require stitches.
Most skin biopsies are performed in the outpatient setting and are quick procedures.
Lab Analysis
For routine histopathology, the tissue is usually preserved in formalin, processed into very thin sections, stained, and examined under a microscope.
The pathologist may assess:
- The arrangement of skin layers
- Cell shape and appearance
- Inflammation and its distribution
- Signs of infection
- Abnormal pigment-producing cells
- Precancerous or cancerous changes
- Whether a lesion has been fully removed, when relevant
Additional work may include special stains, immunohistochemistry, fungal or bacterial studies, or molecular tests. More specialised analysis can extend the reporting time.
How to Understand Skin Biopsy Results?
A skin biopsy does not have a numerical normal range. The report describes what the pathologist sees.
Benign or Non-cancerous Finding
No cancer is identified. The report may diagnose a benign mole, cyst, wart, inflammatory condition, or another harmless growth.
Inflammatory or Autoimmune Finding
The tissue pattern may support a diagnosis such as psoriasis, eczema, lupus, vasculitis, or a blistering disorder. Sometimes the result narrows the possibilities without identifying one condition with complete certainty.
Infectious Finding
Fungal, bacterial, viral, or other infectious changes may be seen. Culture or molecular testing may still be needed to identify the organism.
Atypical or Precancerous Finding
Abnormal cells are present but may not be considered invasive cancer. It may be recommended to remove, resample, or follow more closely.
Malignant Finding
Cancer cells detected. The report will describe the type of cancer, depth, margins, and other features which help guide further treatment.
Non-diagnostic Finding
Occasionally, the sample is too small, too superficial, taken from the wrong area, or altered by previous treatment. A repeat or different type of biopsy may then be needed.
“The reference ranges vary depending on the laboratory and the methodology used. Individuals must consult their healthcare provider for correct interpretation of the results.”
What Can You Expect After the Biopsy?
Mild soreness, bruising, or a small amount of bleeding can occur. A scar is also possible, although it often becomes less noticeable with time.
Follow the clinician’s wound-care instructions. These may include:
- Washing your hands before touching the area
- Gently cleaning it with mild soap and water
- Applying a thin layer of petroleum jelly if advised
- Applying a clean dressing over it.
- Avoiding swimming or soaking until the wound has healed
- Returning for stitch removal when required
Moisturise and cover the wound to promote healing and prevent scabbing. Biopsy sites on the lower legs and feet may take longer to heal than sites elsewhere.
Contact your healthcare provider if you develop worsening pain, persistent bleeding, increasing redness or swelling, pus, fever, or warmth around the site.
What Happens if Test Results Show Abnormal Findings?
Depending on the diagnosis, the next step will follow.
Follow-up may consist of:
- Treatment of an inflamed or infected skin condition
- Removal of residual abnormal tissue
- Larger excision if cancer develops
- Other stains or laboratory molecular tests
- Biopsy repeat
- Other skin exam or imaging
- Referral to dermatology, surgery, or oncology.
Biopsy is tissue proof. The final plan is also determined by the location, size, depth, symptoms, and medical history of the patient and lesion.
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