A hole left after the drainage of a powdery tumor is actually the cyst wall around the powdery tumor, which usually needs to be cured by elective complete removal of the cyst wall after the drainage is clean and the surrounding inflammation has subsided. Pemphigoid is a common term for what is clinically known as a sebaceous cyst. Due to the contents of the powdery tumor, which are often compared to bean curd-like, it is prone to secondary bacterial infection and even abscess formation, which usually requires drainage when an abscess is formed. Sebaceous cysts are surrounded by an intact cyst wall, so it is usually impossible to achieve a single cure by drainage alone. Therefore, in clinical practice, the cyst is usually completely removed along the wall of the cyst at an optional stage after the drainage is clean and the inflammation has subsided, in order to achieve a cure, otherwise the sebaceous cyst will recur again.