Epidermal lipids and scaling diseases of the skin.

Alterations in epidermal lipid content or metabolism underlie several scaling diseases of the skin in man and experimental animals. The importance of cholesterol to epidermal homeostasis and normal desquamation is demonstrated by the scaling disorder produced by topical applications of lovastatin in experimental animals, and by the imbalance of the cholesterol sulfate:cholesterol ratio in stratum corneum in patients with recessive X-linked ichthyosis. The essential fatty acid-deficient rodent illustrates the importance of linoleic acid to epidermal function. Finally, a defect in lamellar body organellogenesis may underlie harlequin ichthyosis.