Dysplastic naevi: the controversy continues

Key Points

  • The entity ‘mildly dysplastic naevus’ has been removed from the World Health Organisation’s classification of dysplastic naevi.
  • Dysplastic naevi are now to be graded as ‘low grade dysplastic naevus’ (previous moderately dysplastic naevus) or ‘high grade dysplastic naevus’ (previous severely dysplastic naevus).
  • Current data suggest no further treatment is necessary for lentiginous junctional/compound naevi and dysplastic naevus with low grade dysplasia (previous mildly dysplastic and moderately dysplastic naevi) with clear histologic margins and no pigment evident clinically, unless there was a high level of prebiopsy clinical concern.
  • Re-excision with a 2-5mm clinical clearance is recommended for high grade dysplastic naevi (previous severely dysplastic naevi) with involved histologic margins.
  • There is growing evidence that observation may be reasonable for low grade dysplastic naevi (previous moderately dysplastic naevus) if they were excised with clinically clear margins/ no residual clinical pigment is observed, despite histologically involved margins. More data may be required before this is accepted into clinical practice.
  • There does not appear to be a clear consensus regarding whether high grade dysplastic (previous severely dysplastic) naevi require re-excision, if initially excised with clear margins, albeit less than 2mm.

Dysplastic naevus: the controversy since the 1970s

The entity of dysplastic naevus has been shrouded in controversy since first described in the 1970s.1 This appears to be due to:

  1. Interobserver differences between histopathologists in applying the previous three tier grading system for dysplasia
  2. Perceived risk of progression to melanoma, and
  3. The possibility of benign entities simulating melanoma, all of which contribute to uncertainty and variability in management.2, 3

Dysplastic naevi are benign neoplasms of melanocytes.3

Dysplasia in melanocytes may occur de novo or in association with either ...

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