Sebaceous gland cysts are striated sebaceous cysts, also known as comedones, which are caused by obstruction of the sebaceous ducts, resulting in the sebum secreted by the sebaceous glands not being able to be drained out, which accumulates to form cysts. They are very common in the clinic and are mainly found in areas with abundant sebaceous glands, such as the cheeks and back. They may start out as soybean-sized cysts, but the more they accumulate, the more they may grow to the size of a peanut or even a fava bean. There are no conscious symptoms, just slightly elevated on the surface of the skin, and there may be small black dots and black mouths at the top, sometimes extruding tofu dregs-like material, sometimes accompanied by a foul odor. Typical sebaceous cysts, which are called epidermoid cysts in clinical practice, have no conscious symptoms, but are inflamed with localized redness, swelling and pain, and may need to be treated in the hospital when inflamed.