Epidermoid cysts are asymptomatic, dome-shaped lesions that often arise from a ruptured pilosebaceous follicle. The minimal excision technique for epidermoid cyst removal is less invasive than complete surgical excision and does not require suture closure. The procedure is easy to learn, and most physicians experienced in skin surgery can perform the procedure after three to five precepted sessions. It involves making a 2- to 3-mm incision, expressing the cyst contents through compression and extracting the cyst wall through the incision. Gauze or a splatter shield should be used to protect the physician from spraying of cyst contents. The rarity of associated cancer makes histologic evaluation necessary only if unusual findings or clinical suspicion of cancer is present. Inflamed cysts are difficult to e excise, and it is often preferable to postpone excision until inflammation has subsided.
Epidermoid cysts are asymptomatic, slowly enlarging, firm-to-fluctuant, dome-shaped lesions that frequently appear on the trunk, neck, face, scrotum or behind the ears. Occasionally, a dark keratin plug (a comedo) can be seen overlying the cyst cavity. These epithelial, walled cysts vary from a few millimeters to 5 cm in diameter. The cysts are mobile unless fibrosis is present.
The term “sebaceous cyst” has fallen into disuse; current terms include epidermal cyst, keratin cyst, epithelial cyst, and epidermoid cyst. Other types of cysts are included in Table 1. Epidermoid cysts often arise from a ruptured pilosebaceous follicle associated with acne. Duct obstruction of a sebaceous gland in the hair follicle can result in a long, narrow channel opening in the surface comedo. Other causes include a developmental defect of the sebaceous duct or traumatic implantation of surface epithelium beneath the skin.
The cysts contain keratin and lipid, and the rancid odor often associated with these cysts relates to the relative fat content, bacterial infection, or decomposition. Spontaneous rupture discharges the soft, yellow keratin material into the dermis. A tremendous inflammatory response (foreign-body reaction) ensues, often producing a purulent material. Scarring makes removal more difficult.