Epidermoid cysts have been clinically reported to be cancerous, but the probability of epidermoid cysts becoming malignant is very low. Epidermoid cyst, also known as epidermoid cyst, is one of the common skin cysts, which appears as a cyst of normal skin color or greenish-gray color, some of which can be seen as a black opening in the center of the cyst and can squeeze out bean curd-like material at the opening. Epidermoid cysts are mostly benign and rarely become malignant. If the cysts show signs such as recent rupture, significantly accelerated growth and repeated infections, they suggest possible malignant changes and should be treated at the hospital as soon as possible.