New understandings of the pathogenesis of acne

of the pathogenesis of acne Pennsylvania Acne vulgaris is the most common skin disease, affecting nearly 80% of young adults aged 11 to 30.'Not only can it cause disfiguration and permanent scarring, but it can have an adverse effect on psychologic development, resulting in profound emotional scarring, which may lead to social phobias, withdrawal from society, and clinical depression2Research during the past three decades has confirmed the multifactorial origins of the disease.Even the most difficult cases may now be controlled by using rational therapies based on current concepts of pathogenesis.This article reviews the pathophysiologic factors that influence the development of acne,3 most notably ( 1) excessive sebum production, (2) abnormal desquamation of sebaceous follicle epithelium (comedogenesis), and (3) proliferation of Propionibacterium acne+ resulting in inflammation. SEBACEOUS GLANDS AND SEBUMThe pilosebaceous unit consists of sebaceous glands and hair follicles.Sebaceous glands and hair follicles are physically connected and usually vary inversely in size.These units are located in all skin areas except the palms and soles.There are approximately 900 glands per square centimeter on the face (particularly at midface), upper neck, and chest.The rest of the body averages fewer than 100 glands per square centimeter."Free" sebaceous glands (those not attached to a hair follicle) that open to the surface of the skin are present in the meibomian glands of the eyelid, the areolae of the nipples, and