A discussion of why partial biopsies of melanocytic lesions may not be representative of the entire lesion

1. Partial biopsies of melanocytic
lesions
Dr Ian Katz – March 2013

2. • Partial biopsies of melanocytic lesions may not
be representative of the entire lesion

3. • In sun damaged skin of older patients, often
get areas of actinic keratosis, seborrhoeic
keratosis, solar lentigo, mildly atypical
lentiginous hyperplasia, and melanoma
• All in the same lesion and this may confuse a
partial biopsy

4. Case 1
• 57 yo man with mildly atypical pigmented
lesion on dermoscopy

5. Case 1 – original shave

6. Case 1 – original shave

7. Case 1 – wider excision

8. Case 1 – wider excision

9. Case 1 - summary
• Mildly atypical naevus on biopsy
• Melanoma on wider excision

10. Case 2
• 60 yo man with pigmented lesion on arm –
clinical question ? Pigmented BCC
• Punch biopsy taken – quite OK here

11. Case 2 – original biopsy

12. Case 2 – wider excision

13. Case 2 – wider excision

14. Take home messages
• Partial biopsies of melanocytic lesions are not
encouraged
• Sometimes OK if:
– Question is melanocytic or not?
– Large lesion in anatomically difficult site and trying
to plan surgery
– BUT – get as much tissue as possible and try to get
from most atypical areas, multiple sites

15. Take home messages
• Follow-up patients, especially if margins are
involved or not certain
• Don’t accept comment of dysplastic
naevus, mildly atypical naevus in markedly
sun-damaged skin – most are melanomas