Sebaceous cysts is a general term which encompasses both epidermoid and pilar cysts. It is a bit of a misnomer and probably best avoided where possible.

Epidermoid cysts are due to a proliferation of epidermal cells within the dermis. Pilar cysts (also known as trichilemmal cysts or wen) derive from the outer root sheath of the hair follicle.

Location: anywhere but most common scalp, ears, back, face, and upper arm (not palms of the hands and soles of the feet).

They will typically contain a punctum.

Excision of the cyst wall needs to be complete to prevent recurrence.