What is the procedure for performing a punch biopsy?

How to Perform a Punch Biopsy

A punch biopsy is a simple, effective procedure that involves using a circular blade to obtain a full-thickness skin specimen for diagnostic evaluation of skin disorders.

Indications for Punch Biopsy

• Punch biopsy is the preferred technique for obtaining diagnostic full-thickness skin specimens for histologic examination 1, 2
• Appropriate for diagnosing:
  • Cutaneous neoplasms and pigmented lesions 1, 2
  • Inflammatory skin conditions 2
  • Chronic skin disorders 2
  • Suspected cutaneous leishmaniasis 1
  • Basal cell carcinoma (when full-thickness sampling is needed) 1

Equipment and Preparation

• Circular punch tool (typically 3-4 mm in diameter) 2
• Local anesthetic (e.g., lidocaine with or without epinephrine) 1
• Antiseptic solution for skin preparation
• Sterile gloves
• Forceps and scissors
• Hemostatic agents (aluminum chloride or ferric subsulfate solution) 1
• Suture material (if needed)
• Dressing supplies
• Specimen container with fixative 1

Procedure Technique

1. Site Selection

   • Choose an area representative of the pathology 1, 2
   • For suspected melanoma, select the thickest portion of the lesion 1
   • For ulcerative lesions, sample the indurated border after removing debris/exudate 1

2. Anesthesia

   • Clean the area with antiseptic solution
   • Administer local anesthesia (lidocaine ± epinephrine) 1
   • Note: Avoid epinephrine for lesions on face, genitalia, or digits 1

3. Performing the Biopsy

   • Stretch the skin perpendicular to the lines of least skin tension to create an elliptical wound for easier closure 2
   • Hold the punch tool perpendicular to the skin surface 2
   • Apply downward pressure while rotating the punch in a single direction (clockwise or counterclockwise) 2
   • Continue rotating until the punch penetrates into the subcutaneous fat 2

4. Specimen Retrieval

   • Gently lift the specimen with forceps, gripping the subcutaneous tissue (not the epidermis) to avoid crush artifact 2
   • Use scissors to cut at the base of the specimen to free it 2
   • Handle the specimen carefully to avoid crushing 2

5. Hemostasis and Wound Closure

   • Apply pressure with gauze for initial hemostasis 3
   • For persistent bleeding, use topical hemostatic agents like aluminum chloride or ferric subsulfate 1
   • Small punch sites (≤3 mm) may heal by secondary intention 3
   • For larger punch sites (≥4 mm), close with a single simple suture 2

6. Specimen Handling

   • Place the specimen in appropriate fixative (typically formalin) 1
   • Label the container with patient information and biopsy site 1
   • Complete a pathology request form with relevant clinical information 1

Special Considerations

• Nail Biopsy: Requires removal of the nail plate to access the nail matrix for proper sampling 4
• Oral Mucosal Biopsy: Keep biopsies superficial and avoid neurovascular structures; sites typically heal by secondary intention 3
• Melanoma: Avoid shave biopsies as they may underestimate Breslow thickness; full-thickness punch or excisional biopsy is preferred 1
• Lentigo Maligna: Consider broad shave biopsy extending into deep papillary or superficial reticular dermis to assess for focal microinvasion 1

Complications and Management

• Bleeding: Usually controlled with pressure; persistent bleeding may require electrocautery 3
• Infection: Rare with proper technique; can be prevented with good antiseptic preparation 2
• Scarring: Minimal with proper technique and appropriate wound closure 5
• Pain: Minimal with adequate local anesthesia 5, 2

Contraindications and Cautions

• Avoid in patients with peripheral vascular compromise 4
• Use caution in anticoagulated patients
• For suspected melanoma, avoid punch biopsies >3 mm to permit accurate subsequent lymphatic mapping 1
• Shave biopsies should be avoided for suspected melanoma as they may compromise accurate assessment of Breslow thickness 1