Cyst, Sebaceous (Epidermal Cyst)



  • The term “sebaceous cyst” is a misnomer.
  • The correct nomenclature is “epidermoid cyst” because these structures have no sebaceous gland component (1).
  • Also known as epidermal inclusion cyst and infundibular cyst
  • A benign, encapsulated, subepidermal nodule filled with keratinaceous material produced by the stratified squamous epithelium lining the cyst wall
  • Most commonly located on face, neck, trunk
  • Synonym(s): epidermal inclusion cysts; epidermal cysts; infundibular cysts; keratin cysts; inclusion cysts
  • “True sebaceous cysts” that originate from the sebaceous gland are known as steatocystoma simplex. These are rare.


  • Most common cutaneous cyst
  • Predominant sex: male > female (2:1)
  • Predominant age: most common in 3rd to 4th decades
  • Rare before puberty
  • An estimated 1% of epidermoid cysts are found to have malignant transformation (2).
    • Squamous cell carcinomas are the most common (70%), followed by basal cell carcinoma (10%).

Etiology and Pathophysiology

  • Result from plugging of the follicular orifice
  • May occur by epidermal implantation through deep penetrating injuries
  • Often result from rupture or occlusion of pilosebaceous follicles resulting in the accumulation of keratin in the subepidermal or dermal layer of the skin
  • Spontaneous
  • Damage to hair follicle
  • Ruptured sebaceous gland
  • Congenital trauma (translocation of surface epithelial cells deep to the dermis) (3)

Most cases are sporadic and nonfamilial. Epidermoid cysts are also noted in the following:

  • Gardner syndrome (autosomal dominant)
    • Consider when encountering epidermoid cysts unusual in number or location (e.g., multiple digits or legs) (4), especially if found in conjunction with osteomas.
  • Other genetic syndromes with cystic structures resembling epidermoid cysts such as Gorlin syndrome (autosomal dominant)
  • Pachyonychia congenita type II (autosomal dominant)

General Prevention

Avoid significant sun exposure.

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