Table 2 Histopathological and immunohistochemical features of pre-malignant intraepidermal mimics of melanoma
Intraepidermal mimicHistopathological featuresImmunohistochemical features
Actinic keratosis

  • Partial thickness dysplasia of keratinocytes

  • Pigmentation of keratinocytes in the lower layers of the epidermis in the pigmented variant

  • No extension of melanocytes into neighbouring hair follicles

  • Absence of nesting or crowding of melanocytes at the dermo-epidermal junction

  • S-100 and Mart 1/Melan A are helpful to highlight the epidermal melanocytes and distinguish them from the atypical keratinocytes

  • HMWCK or P63 can be used to highlight the keratinocytes