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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)
    • Sterile pack
    • Cleansing snap-sponge (iodine or alcohol/chlorhexidine)
    • Sterile drape with hole in centre (or 2-3 drapes without holes in)
    • 5ml syringe and 2 needles (1 blunt fill 18G drawing-up needle, 1 orange 25G) for local anaesthetic
    • 4mm sterile disposable biopsy punch x1-3
    • Suturing instrument kit
      • Needle holder
      • Toothed forceps
      • Non-toothed forceps
      • Scissors
    • 4-0 Novafil suture (or similar)
    • Cotton gauze swabs (used whenever needed throughout procedure to dry/clean sterile area)
    • Sterile dressing
    • Equipment to be kept outside of the sterile field
      • 10ml sterile saline
      • Sterile gloves
      • 5ml 1% lidocaine (maximum 3mg/kg – note 1ml 1% lidocaine = 10mg) with or without adrenaline
      • Sample tubes
        • Formalin filled specimen container for histology (must send white page of consent form with this sample)
        • Direct immunofluorescence sample container for direct immunofluorescence (if required, e.g. for bullous disorders, vasculitis, or connective tissue diseases; this sample should be from perilesional skin for bullous lesions; skin punch is wrapped in small part of saline soaked gauze inside tube)
        • White top universal container for microbiology (if required, e.g. for suspected infection)
  • 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
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