Transmission electron microscopy of scalp tape strips indicates that
dandruff scalp possesses abnormal stratum corneum (SC) ultrastructure that is normalized by treatment with small-particle
zinc pyrithione (
ZPT). Similar abnormalities occur throughout the scalp of those with
dandruff, even where no flaking is present. SC abnormalities are consistent with hyperproliferation, including
parakeratosis, lipid droplets within corneocytes, few desmosomes, corneocyte membrane interdigitation, and excessive disorganized intercellular
lipid. Reversal of SC abnormalities would require treatment of the cause(s) of
dandruff, not merely flake removal. A protocol was developed to quantify scalp structural abnormalities by scoring cells from scalp tape strips for yeast number, amount of intercellular
lipid, normal intercellular
lipid structures, prevalence of intracellular lipid droplets, parakeratotic corneocytes, and corneocyte interdigitation. This protocol was used to compare
dandruff and normal SC to
dandruff SC treated with either commercial
ZPT-containing shampoo or a placebo. Treatment with commercial
ZPT shampoo significantly returned SC ultrastructure to normal, suggesting control of the cause of
dandruff.