34-BetaE12 expression in benign and premalignant squamous lesions of skin: relation to cell proliferation (Ki-67)

The antibody 34-betaE12 stains selectively the keratins of basal cells. The aim of this study is to investigate the staining pattern of 34-betaE12 in borderline (keratoacanthomas and solar keratosis), and benign lesions (seborrheic keratoses). The proliferation index Ki-67 staining was also evaluated in these and also in malignant (basal and squamous cell carcinomas) cases. The staining pattern where the 34-betaE12 positive cells found in the basal, suprabasal epidermal layers was called "focal"; and the staining in all layers including upper spinous layer was called "diffuse". Mean proliferation index and the distribution pattern of Ki-67 immunohistochemical expression were assessed. Basal and suprabasal expression of 34-betaE12 significantly predominated in the normal parts of the epidermis, in eight out of 11 seborrheic keratoses (%73), one out of the 19 keratoacanthomas (%5), two out of 11 solar keratosis (18%). Statistical analysis revealed significant differences between mean level of Ki-67 expression of malignant (squamous cell carcinoma, basal cell carcinoma), benign (seborrheic keratoses) and premalignant (solar keratoses, keratoacanthomas) lesions (p<0.01). The distribution of staining pattern for Ki-67 paralleled to the staining pattern of 34-betaE12. Basal cell status assessment completed by 34-betaE12 may resolve some, but not all of the problems in terms of determining the presence of dysplasia.