High frequency of loss of heterozygosity in actinic keratoses, a usually benign disease.

Actinic keratoses (AKs) are focal areas of dysplasia with low risk of progression to squamous cell cancer; many regress spontaneously. Using polymerase-chain-reaction microsatellite analysis, we found that loss of heterozygosity on several chromosome arms, including 17p, 17q, 9p, 9q, and 13q, was common in AKs. More than half the AKs examined showed loss of heterozygosity at four or more loci. The apparent genetic instability of these lesions contrasts with their benign clinical course.