Sebaceous cyst

A sebaceous cyst (a form of trichilemmal cyst; also called: keratin cyst, pilar cyst or wen; more correctly called: epidermal cyst or epidermoid cyst (see ICD-10 L72.0)) is a closed sac or cyst below the surface of the skin that has a lining that resembles the uppermost part (infundibulum) of a hair follicle and fills with a fatty white, semi-solid material called sebum. Sebum is produced by sebaceous glands of the epidermis.
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Sebaceous cyst n. A harmless cyst, especially on the scalp or face, containing the fatty secretion of a sebaceous gland. [more]Sebaceous cyst - Community and Resources

Noun
1. a common cyst of the skin; filled with fatty matter (sebum) that is secreted by a sebaceous gland that has been blocked
(synonym) pilar cyst, wen, steatocystoma
(hypernym) cyst
(hyponym) chalazion, Meibomian cyst

A sebaceous cyst is a rounded swollen area of the skin formed by an abnormal sac of retained excretion (sebum) from the sebaceous follicles.