Enzyme histochemical analysis of cell viability after argon laser-induced coagulation necrosis of the skin.

Reduction of nitroblue tetrazolium chloride, a redox indicator, by nicotinamide adenine dinucleotide diaphorase produces in frozen tissue sections an intense blue cytoplasmic pigment. The activity of this enzyme has been shown to subside immediately upon cell death. Twelve patients with port-wine stains were treated with an argon laser. Frozen tissue sections from biopsy specimens obtained before and 10 minutes, 24 hours, and 48 hours after laser application were processed for nitroblue tetrazolium chloride staining. In normal skin all epidermal and dermal cells displayed dense cytoplasmic blue granular pigment that spared the nuclei. In port-wine stains the laser-induced coagulation necrosis was first seen as an arc-shaped, sharply demarcated, unstained, nitroblue tetrazolium chloride-negative area. Initiation of epidermal repair could be observed in all 48-hour sections. The nitroblue tetrazolium chloride method, when compared with hematoxylin and eosin staining, allowed an easier and more accurate definition of laser injury because of the color difference between damaged and normal tissue.