The proliferating cell nuclear antigen(PCNA), one of the markers for proliferating cells, has been detected in solid human neoplasms. Psoriasis is a benign hyperproliferative disorder of the skin.

This study has been made to investigate if PCNA can be detected in the psoriatic epidermis.

Specimens from 10 patients with psoriasis were stained for PCNA using the one hour immunoalkaline phosphatase technique.

The psoriatic epidermis showed positive nuclear staining in 20%-61% (mean, 45.7%) of keratinocytes.

PCNA seems to be involved in the mechanism of increased epidermal cell proliferation in psoriatic lesions.