Factors responsible for dermally induced epidermal hyperplasia.

The secondary epidermal hyperplasia seen over some dermal lesions can be experimentally induced in the guinea pig by the intracutaneous injection of carrageenan. This paper documents experiments directed to determining the factors that cause this epidermal reaction. Indomethacin, aspirin and polyphloretin phosphate were found to block the epidermal thickening. "Non inflammatory" stretching of the skin induced by a silastic implant caused an increase in the germinative population but no sustained epidermal hyperplasia. Rubbing into the skin a rubefacient cream produced more epidermal hyperplasia than did the base cream alone. It is suggested that the secondary epidermal hyperplasia from dermal abnormalities is multifactorial in its causation but that prostaglandin release might be involved and that increased blood flow may also play a role.