Overview of Epidermoid Cyst

Highlights•The term “sebaceous cyst” has fallen into disuse, current terms are an epidermoid cyst. Other common synonyms include infundibular cyst, epidermal cyst, epidermal inclusion cyst, and epidermoid inclusion cyst. •These cysts are slow-growing, painless masses that elevate the skin and often have a central punctum that represents the plugged orifice of the pilosebaceous follicle. •On ultrasound, they have a round to oval structure, well-circumscribed, avascular mass located in the dermis and subcutaneous tissue along with the phenomena of dorsal acoustic amplification and lateral shadowing. On MRI, epidermoid cysts have slightly hypointense signal intensity on T1-weighted and intermediate to high signal on T2-weighted. The MRI findings of marked restricted diffusion are typical of an epidermoid cyst. •Removal may be accomplished by simple excision or incision.