Etiology The etiology of acne is complex and multifactorial. Its development is mainly related to sex hormone levels, heavy secretion of sebaceous glands, proliferation of Propionibacterium acnes, abnormal keratinization and inflammation of the sebaceous ducts of hair follicles, and genetics. Clinical manifestations of acne Acne vulgaris occurs on the cheeks, forehead, cheeks, chest, back and shoulders. Acne lesions generally have no conscious symptoms, but may be accompanied by pain when inflammation is evident. They can be classified as whiteheads, blackheads, papules, pustules, cystic nodules, etc. Chen Shaofei, Department of Dermatology, The First Affiliated Hospital of Henan College of Traditional Chinese Medicine