Apoptosis identified by DNA fragmentation in epidermal neoplasms.

In the previous study, we demonstrated apoptotic cells in basal cell carcinomas by means of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). Positive staining cells were present at the peripheries and centers of the nests. The number of positive cells increased in cases showing deep infiltration. We also stained other epidermal neoplasms using this modified TUNEL method. In squamous cell carcinomas, many positive cells were observed in poorly differentiated types, but only a few cells were stained in well-differentiated types. TUNEL positive cells were rare in Bowen's disease. No positive cells were seen in seborrheic keratosis or verruca vulgaris. Our studies showed that apoptotic cells were more common in rapid growth neoplasms than in slow growth neoplasms.