Actinic Keratosis: Classification

Clinical classification of actinic keratoses (according to Olsen).

Grade according to Olsen Description
I Mild actinic keratosis: single or few, millimeter-sized, rough, blurred skin lesions (lesions) that range in color to reddish. Better to palpate than to see.
II Moderate actinic keratosis: advanced lesions, clearly visible and palpable, flat and irregularly raised, with sharp or blurred borders, red, rough keratinizing surface and further spreading. If the surface is more hyperkeratotic (keratinized), actinic keratosis may also be whitish, yellowish or light brown. Good to see and palpate.
III Severe actinic keratosis: prolonged “late” actinic keratoses firmly attached to the subsurface with warty, humpy skin growths and varying in color (white, brown, black) that are firmly fused to the subsurface. Removal of the horny overgrowth presents an erosive background.

Histologic severity classification of actinic keratoses (AK) (by).

Severity Description
AK I Early in situ stage SCC Atypical keratinocytes in basal cell layer and suprabasal, predominantly in lower third of epidermis
AK II Early in situ stage SCC Atypical keratinocytes in the lower two-thirds of the epidermis
AK III In situ SCC Complete enforcement of all epidermal layers with atypical keratinocytes

The following histomorphologic variants should be designated in the presence of actinic keratosis (AK):

  • Atrophic AK
  • Hypertrophic AK
  • Acantholytic AK
  • Pigmented AK
  • Lichenoid AK
  • Bowenoid AK.