Epidermoid cysts are mostly referred to as epidermoid cysts, a type of cyst containing keratin within the dermis, which may be primary and partly originate from damaged hair follicle structures. The other part is mostly considered to be related to skin injury, surgery and other factors, the details are analyzed as follows: 1. Primary: due to ectopic embryonic epithelial cells during embryonic development. 2. Skin injury: especially knife stab wounds, knife stab wounds are easy to make part of the cells of the epidermis through the wound into the tissue inside or subcutaneous formation of epidermal cysts. 3. Surgery: e.g. episiotomy and suture, perineal repair. Epidermal cysts can be caused if a small amount of epidermis is implanted into the dermal tissue during or after surgery. Most epidermal cysts cause no particular discomfort and do not require treatment. However, if the patient experiences intolerable redness, swelling, heat, or pain, he or she needs to be actively seen for targeted treatment.