- most common premalignant skin condition
- 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
Note1 - 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 (1).
Note2 - there has been tremendous variation in the reported rate of progression of lesions to invasive SCC (from 1:1,000 to 1:5). However the general concensus favours the former, rather than the latter, estimate (2).
Last reviewed 08/2021