Epidermoid cyst

**Definition:** A cutaneous cyst with an epidermoid wall filled with keratin and its breakdown products. It most commonly forms as the result of squamous metaplasia in a damaged sebaceous gland but may result from trauma (traumatic inclusion cyst), especially when situated on the extremities. It typically presents as a spherical skin-coloured or yellowish nodule, often with a central pore opening onto the skin surface.

**Inclusions:** - Epidermal inclusion cyst