A quantitative histochemical study of three oxidative enzymes in solar keratoses and Bowen's disease

Succinate dehydrogenase (SDH), glucose-6-phosphate dehydrogenase (G6PDH) and lactate dehydrogenase (LDH) activities have been studied using quantitative enzyme histochemical techniques in the epidermis of five patients with solar keratoses and Bowen's disease. 'Non sun-exposed' buttock skin was compared with the skin from the actual lesion and adjacent, clinically normal paralesional skin. SDH activity was significantly increased in the basal layer and decreased in the granular layer in the epidermis of both lesion and paralesional skin, although the total epidermal activities were unchanged when compared to 'non-exposed' buttock skin. G6PDH activity was increased in the granular layer of paralesional epidermis and of lesions. No change in LDH activity was detected. Inclusion of phenazine methosulphate in the reaction mixtures resulted in a three-fold increase in formazan deposition without altering the localization. It is concluded that the quantitative changes and alteration in localization of SDH and G6PDH reported in solar keratoses are accompanied by similar changes in adjacent, clinically normal 'sun-exposed' skin and differ from normal 'non-exposed' skin. It is suggested that these changes may precede the development of the solar keratoses and that these findings may indicate a significant metabolic alteration in the events that lead to neoplasia.