Partial biopsies of melanocytic lesions

Dr Ian Katz – March 2013

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

• 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

Case 1

• 57 yo man with mildly atypical pigmented lesion on dermoscopy

Case 1 – original shave

Case 1 – original shave

Case 1 – wider excision

Case 1 – wider excision

Case 1 - summary

• Mildly atypical naevus on biopsy• Melanoma on wider excision

Case 2

• 60 yo man with pigmented lesion on arm – clinical question ? Pigmented BCC

• Punch biopsy taken – quite OK here

Case 2 – original biopsy

Case 2 – wider excision

Case 2 – wider excision

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

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