Acne refers to acne, and chin acne may be caused by the proliferation of Propionibacterium acnes, abnormal keratinization of sebaceous gland ducts in hair follicles, and overproduction of sebum. 1. Proliferation of Propionibacterium acnes: Propionibacterium acnes can break down sebum and cause inflammatory reactions, which can result in chin acne. 2. Abnormal keratinization of follicular sebaceous gland ducts: duct obstruction due to hyperkeratinization of the follicular opening can affect the normal shedding of epithelial cells and sebum discharge, which can result in a circle of chin acne. 3. Excessive sebum secretion: during puberty, androgen levels are high, and under the action of androgen, sebaceous glands can secrete a large amount of oil, which can lead to a circle of chin acne. It is recommended to go to the hospital in time to clarify the cause of the acne and standardize the treatment under the guidance of the doctor.