If you have dense small particles on your forehead, you should consider having acne or fatty grains, which are divided into two types: cornea and sweat duct tumor. The lesions of the above cases are shown to be higher than the surface of the skin, and present multiple, patchy occurrence, so they can be shown on the forehead as dense small particles. Common causes and treatments 1, acne: divided into whitehead acne and blackhead acne, whitehead acne is closed acne, manifested as skin-colored papules, usually the size of a pinhead, the follicle opening is not obvious, not easy to squeeze out the fat plugs. The main causes are increased androgen and sebum secretion, abnormal keratinization of the follicular sebaceous ducts, and excessive consumption of sweets. A retinoic acid ointment can be used to help dissolve and expel the pimples. For acne that has progressed to a late stage and is infected with bacteria, peroxymethylphenidate can be used, as well as antibiotics, such as erythromycin or clindamycin, which are commonly used. For patients with inflammatory reactions, the use of azelaic acid can reduce bacteria on the skin surface, in the hair follicles and sebaceous glands, and especially has an inhibitory effect on Propionibacterium acnes and acne production. 2. Cornu Cervi Pilaris: A benign swelling or retained cyst originating from the epidermis or epithelium of the appendages. It can occur at any age and gender, and can also be seen in newborns. Post-traumatic cornea often occurs after abrasion, scratching or facial inflammatory rash, and is commonly seen in the damage of cutaneous exoporphyria or herpetic epidermolysis bullosa, or after herpes zoster blisters, and some patients have genetic factors; 3. The rash is often enlarged during pregnancy, premenstruation or estrogen use, and is considered to be endocrine-related. It is usually treated with topical retinoic acid, chemical peeling, surgery, microwave ionization, and freezing, laser, ultra-pulse laser or fractional laser. Patients are advised to avoid using heavy, greasy skin care products in their daily life, which can cause sebum to be covered by keratin and not properly discharged to the epidermis and thus accumulate in the skin, and to perform regular skin cuticle cleaning. In addition, patients are advised to minimize the consumption of sugary, or spicy and stimulating food, which can easily induce or aggravate the skin lesions.