Epidermal lipid metabolism in psoriasis and lichen simplex.

The rate and pattern of epidermal lipogenesis from [14C] glucose were measured in fifteen patients with psoriasis and three with lichen simplex, compared with twenty controls. In 'uninvolved' epidermis from psoriatic subjects the mean lipogenic rate was slightly raised, although the increase was not statistically significant. There was a positive correlation between overall lipogenic rate and the percentage of isotope appearing in free sterol, while the relative proportions of the other lipid classes were unchanged. By contrast, in control epidermis sterol percentage was negatively correlated with lipogenic rate. In psoriatic lesions total epidermal lipogenesis (per unit surface area) was raised compared with matched control 'uninvolved' epidermis. Also raised were percentage labelling of free sterol and of combined (free sterol and monoesters), and the free sterol: monoester ratio was increased. Similar findings were obtained with lesions of lichen simplex, suggesting that disturbed sterol metabolism may be a common feature in conditions of abnormal keratinization.