Aneuploidy in actinic keratosis and Bowen's disease--increased risk for invasive squamous cell carcinoma?

The value of DNA single cell cytometry for the detection of aneuploidy was assessed in 100 specimens of actinic keratoses and 39 specimens of Bowen's disease. Ten seborrhoeic keratoses and 10 samples of normal epidermis served as negative control groups. Monolayer smears, prepared from formalin-fixed, paraffin-embedded tissues, were Feulgen-stained and used for interactive DNA-cytometry. In each specimen, the DNA content of 150 randomly chosen squamous epithelial cells was measured, using a TV-image analysis system (TAS-plus, Leica, Germany). Aneuploidy was diagnosed if at least three nuclei with a DNA content above 5c (5cEE > or = 3) were found. The aneuploidy rate in actinic keratosis was 69% (69 of 100) and in Bowen's disease was 95% (37 of 39). Another 20 specimens of actinic keratoses and the remaining two specimens of Bowen's disease were diagnosed as suspicious for aneuploidy (0 < 5cEE < 3). The 20 specimens of seborrhoeic keratoses and normal epidermis did not show any nuclei above the 5c level, and were classified as non-aneuploid. This indicates a sensitivity of 76% (106 of 139) and a specificity of 100% (20 of 20). The frequent occurrence of aneuploidy in actinic keratoses and Bowen's disease underlines the character of the lesions as epidermal carcinomas in situ, but does not explain the long-term low incidence of invasive growth.