Punch biopsies for the Dermatological Nurse

1. Punch biopsies for the Dermatological Nurse Daniel Hewitt FACD

2. Today... 1. Why do a punch biopsy? Advantages and disadvantages 2. Steps in doing the best possible punch biopsy Local anaesthetic Punch biopsy technique Suture 3. Practice!!

3. Why do a punch biopsy? Biopsies are required when histopathological examination will facilitate optimal management They may clarify a diagnosis or assess depth of a tumour Biopsy choices... Punch biopsy Shave biopsy Saucerization Curette biopsy Incision biopsy Excision biopsy Scissor/snip

4. Punch biopsy advantages Relatively easy, quick and cheap Small and sutured therefore leaves minimal scar (important for facial biopsies) Allows vertical histological analysis Samples epidermis and full thickness of dermis • depth of pathology in cancer cases and • patterns of pathology in inflammatory lesions

5. Punch biopsy disadvantages Small specimen which may be inadequate for diagnosis in difficult cases False negative or incorrect diagnosis is more likely with 2mm punch due to sampling error or inadequate specimen

7. The punch biopsy involves... Local anaesthetic pharmacology optimal techniques to maximize effect, minmize pain Punch biopsy itself optimal technique Suturing simple interrupted suture

8. Local anaesthetic Procaine, benzocaine Lignocaine, Bupivacaine, Prilocaine

9. Amides (especially lignocaine) used often as Rapid onset of action Longer duration of action Rarely induce allergy

10. Lignocaine Rapid onset 1-5 min Medium duration 30-120 min Crosses blood-brain barrier Crosses placenta (Category A) Crosses into breast milk Metabolised by liver 90%

11. Lignocaine precautions Advanced liver or renal disease Epilepsy, myasthenia gravis Cardiac conduction defects: WPW, Stokes Adams, antiarrhythmics (amiodarone)

12. Adrenaline Absolute Contraindications Severe hypertension Pheochromocytoma Hyperthyroidism Severe hypertension Severe peripheral vascular occlusive disease Relative: unstable angina, recent MI, recent CABG, acute angle glaucoma, medications (tricyclics, MAO inhibitors, B blockers, Digoxin, cocaine user, antihistamines in cough syrup)

13. Adverse reactions

14. Lignocaine toxicity

15. Optimal pain control Reduce anxiety Calm environment Patient reclined Second person holding patient’s hand Reassurance, distraction

16. Injection technique Warm the solution Stretch or pinch the skin 27G or 30G needle Inject solution slowly Into subcutaneous tissue, then dermis Inject from direction of nerve supply Re-insert needle into previously numbed area or through wound edge

17. Punch Biopsy Technique Stretch the skin tightly in the opposite direction to the line you want the scar in Twist the instrument to cut into the skin

18. Delicately remove punch biopsy tissue Suture the oval defect Simple dressing

19. The square knot The standard knot tie 2 throws on the first pass and 1 throw on the second and third pass.

20. Suturing principles Be gentle with the tissue Sutures must be placed at the same vertical level across the wound to prevent step off deformity Proper placement of sutures will approximate and evert wound edges producing the best possible scar When sutures are tied the wound edges should be gently touching and slightly everted for best results