Pathogenesis of Acne Follicular disease, comedo formation Produced by the impaction and distension of the follicles with a keratinous plug in the lower infudibulum

Hyperproliferation and abnormal differentiation of keratinocytes increased sebum secretion

Lower portion of follicle is dilated by retianed/entrapped sebum and keratinous materials

Disruption of follicular epithelium permits discharge of follicular contents into the dermis Bacteria, keratin and sebum leads to release of proinflammatory mediators and accumulation of T helper cells, neutrophils and giant cells Formation of inflammatory papules, pustules

Marked inflammation causes nodulocystic lesions

Provocative Factors Comedogenic, greasy, occlusive products Ex. Pomade or gel used on the hair Mechanical and frictional forces Ex. Tight strap on a sports helmet Repeated laser hair removal Genetic factors Hyperandrogenic states (PCOS), menstruation Prolonged use of topical or oral steroids Other skin irritants or chemical/industrial compounds Make up, overexuberant washing

Histopathology Comedones Pustular Nodular Thinned epithelium and a dilated follicular canal filled withlamellar lipid-impregnated keratinous materials Pustular Folliculocentric abscess surrounded by dense inflammatory exudate of lymphocytes and PMNs Nodular Indolent, contain plasma cells, foreign body giant cells, proliferation of fibroblast