Incisional Biopsy: Sampling a Large or Complex Skin Lesion

What Is an Incisional Biopsy?

A biopsy is the medical term for removing a small piece of tissue to examine it under a microscope. There are several biopsy techniques used in dermatology, and the right one depends on the type and size of the lesion.

An incisional biopsy specifically means making an incision (a cut) to remove only part of a lesion for sampling—leaving the rest of the lesion in place. This is different from an excisional biopsy, which removes the entire lesion.

Think of it this way: if you have a large, flat, irregular brown patch on your skin that is several centimeters wide, removing the whole thing in one office visit may not be practical. Instead, your doctor cuts out a small but representative piece—ideally from the most concerning-looking part—sends it to pathology, and then uses those results to plan the right treatment.

When Is an Incisional Biopsy Used?

Dermatologists choose incisional biopsy in specific situations:

• Large lesions: When a lesion is too wide to remove entirely with a simple excision in one visit (for example, a large lentigo maligna—a type of early melanoma that can span several centimeters on sun-damaged skin)
• Diagnosis before major surgery: When knowing the exact diagnosis first would change how the lesion is treated (for example, whether Mohs surgery vs. standard excision is more appropriate)
• Inflammatory or systemic skin conditions: Large plaques from conditions like psoriasis, lichen planus, or cutaneous lymphoma may require an incisional sample from the thickest or most active area
• Deep or complex lesions: When a superficial shave or punch biopsy would not capture enough tissue depth to make a diagnosis
• Tumors on sensitive areas: Where a full excision would need extensive planning for reconstruction beforehand

What Happens During the Procedure

An incisional biopsy is a minor office procedure done under local anesthesia:

1. Choosing the site: Your doctor examines the lesion and selects the area most likely to yield a useful diagnosis—often the most raised, darkest, or most irregular part. They may use a dermatoscope (a handheld magnifying device) to guide selection.
2. Numbing the area: A small amount of local anesthetic (lidocaine with epinephrine) is injected around the biopsy site. You will feel a brief sting. Within a minute or two, the area is numb.
3. Making the incision: Using a scalpel, the surgeon makes an elliptical or wedge-shaped cut and removes a piece of tissue that includes the full thickness of the skin—from the surface down through the deepest layer of the lesion.
4. Controlling bleeding: Bleeding is stopped with pressure or light electrocautery.
5. Closing the wound: The small biopsy wound is closed with one to a few stitches. This is important because it produces a neater scar and heals faster than leaving it open.
6. Sending tissue to the lab: The sample is placed in formalin and sent to a dermatopathologist. Results are usually available within 5–10 business days.

Recovery and Wound Care

Because an incisional biopsy only removes a piece of the lesion, the wound is generally small:

• Keep the site clean and covered with petroleum jelly and a non-stick bandage for the first 5–7 days.
• Change the dressing daily or when it gets wet or dirty.
• Surface stitches are typically removed in 5–7 days for the face and 10–14 days for the body.
• Avoid picking at or scratching the area. Let any scab fall off on its own.
• Mild soreness for a day or two is normal. Acetaminophen works well for post-procedure discomfort.

The rest of the lesion remains untreated until your pathology results guide the next step. Your dermatologist will follow up to discuss the report and outline a treatment plan.

After the Biopsy: What Happens Next?

Once the pathology report returns, your doctor will explain what was found and what it means for you. Possibilities include:

• Benign: The lesion is non-cancerous and may not need further treatment, or may be monitored.
• Pre-cancerous or dysplastic: A wider excision or other treatment may be recommended.
• Cancerous: The type, depth, and characteristics of the cancer will guide whether standard excision, Mohs surgery, or another approach is best.

You will not need to “wait and see” without a plan—your biopsy results will give your doctor the information needed to act.

When to See a Dermatologist

• You have a large, irregularly shaped, or multicolored spot on your skin that has changed or grown
• A flat pigmented lesion is spreading or developing raised areas within it
• You have a chronic skin rash or plaque that has not responded to treatment and has not been biopsied
• Your biopsy wound is not healing, is getting more red and swollen, or has pus—contact your doctor
• You are waiting on results and the wait is causing anxiety—call your doctor’s office; they can usually give you an update

Frequently Asked Questions

Why doesn’t the doctor just remove the whole lesion?

For large or complex lesions, removing the entire thing without knowing the diagnosis can create problems. For example, a large melanoma requires a specific margin width and sometimes a sentinel lymph node biopsy—not just a simple excision. Getting the diagnosis first means the full treatment is done right the first time, with the right technique and margins.

Could the biopsy miss the cancer?

It is possible. Because only a sample is taken, a small area of cancer could potentially fall outside the sample. This is why your doctor carefully selects the most suspicious-looking part of the lesion to biopsy, and why close follow-up is important if the biopsy is benign but the lesion looks worrying. If a lesion keeps growing or changing after a benign biopsy result, a repeat biopsy from a different area may be needed.

Will the biopsy scar be permanent?

A small scar will form at the biopsy site. Since this is a small incision that is sutured closed, it heals into a fine line that fades over 12–18 months. In most cases this scar is barely noticeable at follow-up visits, especially compared to what a wound would look like if left open without stitches.

How long until I know the results?

Routine dermatopathology results typically take 5–10 business days. If the case is complex or requires special staining techniques, it may take up to two weeks. Your doctor’s office will contact you with results, but you can also call to check in if you have not heard within 10 days.

Trusted Resources

• American Academy of Dermatology – Skin Cancer
• Skin Cancer Foundation – Treatment Options
• Mayo Clinic – Skin Biopsy

Always consult a board-certified dermatologist or dermatologic surgeon for diagnosis and treatment recommendations specific to your situation.