Sebaceous cyst removal is a medical procedure performed to excise a sebaceous cyst, which is a noncancerous, closed sac-like structure filled with a thick, cheese-like substance called keratin. These cysts form under the skin, often in areas with a high concentration of sebaceous glands, such as the face, neck, and upper body. Removal is typically done for cosmetic reasons or if the cyst becomes infected or causes discomfort.