The diagnosis of acne is generally easy to make based on the typical clinical manifestations of acne vulgaris, which commonly occurs in young people, red papules on the face and upper chest and back, follicular papules, and yellowish-white seborrheic plugs that can be squeezed with the fingers. Differential diagnosis: This disease should be differentiated from occupational acne and facial disseminated lupus cornea. 1. Occupational acne can be divided into two categories: oil acne and chloracne, depending on the exposure: oil acne is related to long-term exposure to petroleum, coal tar and their fractionation products. It occurs in contact with exposed areas. The lesions are blackheads or folliculitis, with enlarged follicle openings and fractured fine hairs at the follicle openings, and may appear as keratotic acne-like lesions, as well as pustules and cysts. Chloracne is associated with long-term exposure to halogenated hydrocarbon compounds. It occurs on the face and around the ears, and can also involve the trunk, extremities, and scrotum. The lesions are predominantly blackheads, and inflammatory papules are less common. Some patients may have straw-yellow cysts around the ears and in the scrotum. Mild organ damage is considered to be one of the characteristics of chloracne. 2. Facial disseminated milia are prevalent in adults, and the lesions are mainly hemispherical papules or small nodules, dark red, with jam-colored dots showing when the slide is pressed, and applesauce-colored changes visible on slide pressure. The damage is not consistent with the hair follicles and is symmetrically distributed, and the lesions often fuse into a dike in the lower eyelid. Pathologic and etiologic examinations allow objective identification of the two diseases.