Last edited 02/2022 and last reviewed 02/2023

  • Most common premalignant skin condition.
  • Dysplastic proliferations of keratinocytes with a potential for malignant transformation (1).
  • Characterized by multifocal scaly, hyperpigmented or scaly lesions, usually brown with a scaly base.
  • Histologically they are characterised by marked thickening of the keratin layer (hyperkeratosis) and the prickle cell layer (acanthosis). There may be a variable degree of dysplastic change and abnormal mitotic activity. However the basal layer remains intact.

Note 1 - there is debate whether actinic keratoses are premalignant conditions or alternatively early-stage squamous cell carcinoma (SCC). In a study of 459 patients with cutaneous SCC, there were associated adjacent actinic keratoses in 97% of the cases of cutaneous SCC (2).

Note 2 - there has been tremendous variation in the reported risk of progression of actinic keratosis to invasive SCC (between 0.025% to 16% per year). There is currently no existing technology to distinguish between actinic keratosis lesions that will clear, remain stable, or progress to invasive disease. (3)

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