Punch biopsy of the skin [advanced]

Introduction

• Wash hands, Introduce self, Patients name & DOB & wrist band, Explain procedure and get written consent
  • Common risks: scarring, bleeding, infection, damage to local structures, nerve damage, numbness over area

Preparation part

• Wash hands and apply apron
• Clean a trolley
• Gather equipment onto bottom of trolley (think through what you need in order)

• Walk to patient
• Wash hands
• Open sterile pack to form a sterile field on the top of the trolley
• Open packets (without touching the instruments themselves) and drop sterile instruments neatly into the sterile field
• Pour some sterile saline over a gauze so it is moist
• Pick up waste bag from sterile pack without touching anything else and stick to side of trolley

Patient part

Positioning and exposure

• Choose and expose biopsy site
  • Ideal areas: arms, thighs, back, abdomen
  • Ideally biopsy an established lesion with the most primary inflammatory change (unless blistering/pustular/vasculitic lesion, then early lesions preferred)
  • Part of lesion to biopsy
    • For large lesions, biopsy the edge of the lesion, the thickest part, or the most abnormal area
    • For annular lesions, biopsy the edge of the lesion
    • For ulcers, biopsy the edge and include a portion of normal skin
    • NB. in bullous skin lesions, the skin biopsy for direct immunofluorescence should be taken from perilesional skin.
  • Areas to avoid if possible
    • Sites with underlying nerves or blood vessels
    • Cosmetic-sensitive areas (e.g. face; shoulders and chest are prone to hypertrophic scarring)
    • Areas with high infection risk (e.g. groins, axillae)
    • Areas of vascular insufficiency (e.g. lower legs/feet)
    • Lesions with secondary features (e.g. infection/crusting)
    • Lesions that have been subjected to trauma (e.g. scratched lesions, lesions over joints)
• Position patient comfortably
• Mark biopsy site(s) with a skin pen/indentation

Preparation

• Wash hands
• Apply sterile gloves using sterile technique (open pack on a side surface)
• Sterilize area
  • Work from middle outwards in one spiral motion (use cleansing snap-sponge)
  • Discard used snap-sponge as it is no longer sterile, but note all equipment used after this (including all needles) can be returned to the sterile field after use
  • Apply the sterile drape over the site so that the hole is in the correct place to allow access to the biopsy site
• Anaesthetise area
  • Ask assistant to snap open lidocaine bottle and hold open upside-down
  • Draw up lidocaine using drawing-up needle on 5ml syringe
  • Change to the orange needle and insert at an acute angle to anaesthetise the area of the biopsy site (subcutaneously and slightly deeper; 1-2ml per biopsy site)

Performing the punch biopsy

• Stretch skin perpendicular to resting skin lines
• Push biopsy punch directly into skin, rotating it back and forth, as far as it will go (should go through to subcutaneous fat – a ‘giving way’ feeling marks this point)
• NB. in areas of thin skin, do not go down as far as the periosteum. Avoid areas with underlying nerves or blood vessels.
• Remove biopsy punch
• Press down on either side to elevate skin punch
• Grab skin punch very gently with toothed forceps (avoid crush injury), elevate, and cut off at the base with scissors
• Place skin punch on saline soaked gauze in sterile field
• Suture wound with a single suture (parallel to skin tension lines) – see suturing notes
• NB: leave enough thread on the needle end if need multiple biopsies
• Repeat process if multiple biopsies required (different biopsy required for histology, direct immunofluorescence, and microbiology if required)
• Apply a sterile dressing
• Place samples in specimen tubes as detailed below

To complete

• Thank patient and cover them
• Bin waste and gloves, dispose of sharps safely, clean trolley and wash hands
• Label tubes and send to lab, listed as urgent if rapid result required
  • Formalin sample tube (histology) → histopathology
    • Must be sent with white page of patient consent form
  • Direct immunofluorescence sample tube (direct immunofluorescence) → histopathology (if required)
    • Skin punch for this sample should be wrapped in a small part of saline soaked gauze (cut off with scissors)
  • White universal sample tube (MC&S) → microbiology (if required)
• Advice patient sutures must be removed in 10-14 days
• Fully document procedure in patients notes