DermatopathologyAdvancedAnnotated

Melanoma versus dysplastic naevus

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Clinical history

41-year-old with a changing pigmented lesion on the back.

Specimen

Excision biopsy · Stain: H&E

Microscopic description

Asymmetric proliferation of atypical melanocytes with pagetoid upward scatter, confluent junctional nests of varying size and shape, and dermal mitoses.

Diagnostic question

Which architectural and cytological features favour melanoma over a dysplastic naevus?

Reveal differential diagnosis
  • Dysplastic naevus with severe atypia
  • Recurrent naevus
  • Spitz naevus
Reveal final diagnosis

Superficial spreading melanoma, Breslow thickness 0.9 mm

Learning points

  • Asymmetry, poor circumscription and pagetoid spread favour melanoma
  • Dermal mitoses and lack of maturation are important
  • Report Breslow thickness, ulceration and margins

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