Scanning electron microscopic study of tretinoin (vitamin A acid) acne therapy.

Structural differences between untreated and tretinoin treated acne, uniquely evident with the scanning electron microscope, provide insight into the disease and its response to the drug. Early tretinoin therapy is characterized by the appearance of loosely adherent, parakeratotic cells which account for comedo expulsion and a disrupted skin surface. Persistence of the follicular and comedonal alterations account for the prophylactic value of long-term therapy. Meanwhile, the structure of the stratum corneum returns toward normal, with the clinical accommodation to the topical tretinoin.