Small Fiber Skin Punch Biopsy: What to Expect Before, During, and After

If your neurologist has recommended a skin punch biopsy for small fiber neuropathy, you probably have questions about what the procedure involves. Understanding what to expect can help ease any anxiety and ensure you're properly prepared.

In this comprehensive guide, we'll walk you through exactly what happens before, during, and after a small fiber skin biopsy—from your initial preparation through receiving your results.

What Is a Small Fiber Skin Punch Biopsy?

A skin punch biopsy for small fiber neuropathy is a diagnostic procedure that removes tiny circular samples of skin (typically 3mm in diameter—about the size of a pencil eraser) to examine the small nerve fibers within. This test is the gold-standard method for diagnosing small fiber neuropathy (SFN) because it allows direct visualization and counting of epidermal nerve fibers.

The procedure is called a "punch" biopsy because it uses a small cylindrical tool that removes a round core of skin, similar to using a tiny cookie cutter. The samples are then sent to a specialized laboratory where technicians count the nerve fibers and compare your results to normal values.

Before Your Skin Punch Biopsy

Scheduling and Preparation

When you schedule your small fiber skin biopsy at Achilles Neurology Clinic, our team will provide you with specific instructions. Here's what to expect:

No special preparation required:

• No fasting necessary
• No dietary restrictions
• You can eat and drink normally before your appointment

Medications:

• Continue taking your regular medications unless specifically instructed otherwise
• Blood thinners may need to be discussed with your neurologist
• Bring a list of all current medications to your appointment

What to wear:

• Comfortable, loose-fitting clothing
• Shorts or pants that can be easily rolled up above the knee
• The biopsy sites are typically on the lower leg (near the ankle) and upper thigh

What to bring:

• Photo ID and insurance information
• List of current medications
• Any relevant medical records or prior test results

The Day of Your Procedure

Plan for your appointment to take approximately 30-45 minutes total. You do not need anyone to drive you home—the procedure doesn't require sedation and you'll be fully alert throughout.

During the Skin Punch Biopsy Procedure

Here's exactly what happens during your small fiber skin biopsy appointment:

Step 1: Preparation and Positioning (5-10 minutes)

You'll be comfortably positioned, typically lying on an exam table. The neurologist will:

• Confirm the biopsy locations (standard sites are the distal leg near the ankle and the lateral thigh)
• Clean the skin with an antiseptic solution
• Mark the exact biopsy sites

Step 2: Local Anesthesia (2-3 minutes)

Before any samples are taken, local anesthetic is injected to numb each biopsy site. You may feel:

• A brief pinch or sting as the anesthetic is injected (similar to a dental injection)
• Slight pressure as the area becomes numb
• Complete numbness within 1-2 minutes

Step 3: The Biopsy (2-5 minutes)

The actual biopsy is quick:

1. Sample collection: Using a specialized 3mm punch biopsy tool, the neurologist removes a small cylindrical sample of skin
2. Multiple samples: Typically 2-3 samples are taken from different locations (ankle and thigh) to compare nerve density at different points
3. Each sample takes only seconds: The entire biopsy portion is usually complete in less than 5 minutes
4. Hemostasis: Light pressure is applied to stop any minimal bleeding

Step 4: Wound Care (5 minutes)

After the samples are collected:

• Small adhesive bandages (like Band-Aids) are applied to each site
• No stitches required: The 3mm wounds are small enough to heal on their own
• You'll receive care instructions for the biopsy sites

What Does It Feel Like?

Most patients are pleasantly surprised by how easy the procedure is. Common experiences include:

• During anesthesia: Brief pinch similar to any injection
• During biopsy: Pressure or slight tugging, but no sharp pain
• Immediately after: Mild tenderness at the sites
• Overall: Most patients describe it as "much easier than expected"

After Your Skin Punch Biopsy

Immediate Post-Procedure

You can:

• Drive yourself home
• Return to work or normal activities immediately
• Eat and drink normally
• Resume all regular medications

Wound Care Instructions

Proper care of your biopsy sites promotes optimal healing:

First 24-48 hours:

• Keep the bandages dry
• Avoid submerging the sites in water (quick showers are fine, but avoid baths, swimming, or hot tubs)
• Leave the original bandages in place

Days 2-7:

• Change bandages daily or as needed
• Keep the sites clean and dry
• Apply antibiotic ointment if recommended by your doctor
• Watch for signs of infection (increasing redness, warmth, swelling, or discharge)

Days 7-10:

• The sites should be mostly or fully healed
• Small scabs may still be present
• Minimal to no scarring is typical

What to Expect During Healing

The healing process is straightforward:

Activity Restrictions

Most patients have minimal restrictions:

• Exercise: Light activity same day; wait 24-48 hours for vigorous exercise or anything that causes excessive sweating
• Swimming/baths: Avoid for 5-7 days until sites are healed
• Work: Return immediately for most jobs
• Travel: No restrictions

Getting Your Results

How Samples Are Processed

Your skin samples are sent to Therapath, a specialized laboratory that focuses on small fiber analysis. At the lab:

1. Fixation and preparation: Samples are preserved and prepared for analysis
2. Immunohistochemical staining: Special staining techniques highlight the nerve fibers
3. Microscopic analysis: Trained technicians count the epidermal nerve fibers
4. ENFD calculation: Epidermal nerve fiber density is calculated as fibers per millimeter
5. Comparison: Your results are compared to age and gender-matched normative values

Timeline for Results

• Processing time: 2-3 weeks
• Follow-up appointment: Your neurologist will schedule a visit to discuss results
• Detailed explanation: You'll receive a thorough explanation of your ENFD values and what they mean

Understanding Your Results

Your results will indicate:

• Normal ENFD: Nerve fiber density within normal range for your age and gender
• Reduced ENFD: Lower than normal density, consistent with small fiber neuropathy
• Pattern: Comparison between distal (ankle) and proximal (thigh) sites helps characterize the type of neuropathy

Dr. Ntranos will explain your results in detail and, if small fiber neuropathy is confirmed, discuss treatment options tailored to your specific situation.

Frequently Asked Questions

Does a skin punch biopsy for small fiber neuropathy hurt?

The procedure involves minimal discomfort. Local anesthesia is applied before the biopsy, so you only feel slight pressure during sample collection. Most patients report mild soreness afterward similar to a small scrape, which resolves within a few days.

How long does a small fiber skin biopsy take?

The entire appointment typically takes 30-45 minutes. The actual biopsy procedure itself only takes a few minutes—each skin sample is collected in seconds. Most of the time is spent on preparation, numbing, and post-procedure care instructions.

What is the recovery time after a skin punch biopsy?

Recovery is quick and straightforward. The small biopsy sites (only 3mm) heal completely within 7-10 days. No stitches are required. Most patients return to normal activities immediately after the procedure.

How long until I get my skin biopsy results?

Results are typically available within 2-3 weeks after the procedure. The samples are sent to Therapath, a specialized laboratory, where technicians analyze the epidermal nerve fiber density. Your neurologist will schedule a follow-up appointment to discuss the results.

Will the biopsy leave scars?

The 3mm biopsy sites typically heal with minimal to no visible scarring. Any marks that remain are very small and usually fade over time.

Can I drive after the procedure?

Yes. No sedation is used—only local anesthesia at the biopsy sites. You are fully alert and can safely drive yourself home after the procedure.

What if I'm on blood thinners?

Blood-thinning medications should be discussed with your neurologist before the procedure. In most cases, minor adjustments or no changes are needed, but this depends on your specific situation and the medication involved.

Schedule Your Small Fiber Skin Biopsy in Los Angeles

If you're experiencing symptoms of small fiber neuropathy—burning, tingling, numbness, or unexplained pain—a skin punch biopsy can provide the definitive answers you need. At Achilles Neurology Clinic in Beverly Hills, Dr. Ntranos performs small fiber skin biopsies with expert care in a comfortable office setting.

About the Author

Dr. Achillefs Ntranos MD

Board-Certified Neurologist
Achilles Neurology Clinic

Dr. Achillefs Ntranos MD is a board-certified neurologist and MS specialist known for his thorough evaluations and compassionate approach. Originally from Greece, he trained at Johns Hopkins University and Mount Sinai Hospital before founding Achilles Neurology Clinic in Beverly Hills to deliver comprehensive, patient-centered neurological care. He specializes in MS, autoimmune neurology, neuropathy, headaches, and other neurological disorders, blending research-driven insights with personalized treatment plans.

Learn More About Dr. Ntranos(310) 774-7025