Sebaceous cyst

A sebaceous cyst is a cystic mass formed when the excretory duct of a sebaceous gland in the skin becomes blocked, leading to the accumulation of sebum that cannot be discharged. Sebaceous cysts are characterized by a cyst wall formed by the sebaceous duct and contents resembling a tofu-like retention material, hence they are commonly known as epidermoid cysts. They are slow-growing, benign lesions. They are frequently found in areas with a high concentration of sebaceous glands, such as the head, face, and back.