Merck Manual

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Cutaneous Cysts

(Epidermal Inclusion Cyst [Epidermoid Cyst]; Milia; Pilar Cyst; Trichilemmal Cyst [Wen])


Denise M. Aaron

, MD, Dartmouth Geisel School of Medicine

Reviewed/Revised Jan 2022 | Modified Sep 2022
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Epidermal inclusion cysts are the most common cutaneous cysts. Milia are small epidermal inclusion cysts. Pilar cysts are usually on the scalp and may be familial.

Benign cutaneous cysts are classified according to histologic features of the cyst wall or lining and anatomic location. On palpation, a cyst is firm, globular, movable, and nontender; cysts usually vary in size up to 5 cm in diameter. There are several types of benign cutaneous cysts:

  • Epidermal inclusion cysts

  • Milia

  • Pilar cysts (trichilemmal cysts)

Epidermal inclusion cysts (epidermoid cysts) seldom cause discomfort unless they have ruptured internally, causing a rapidly enlarging, painful foreign body reaction and abscess. Epidermal inclusion cysts are often surmounted by a visible punctum or pore; their contents are white, cheesy, and malodorous.

Milia are minute superficial epidermal inclusion cysts that are most often on the face and scalp.

Pilar cysts (trichilemmal cysts) may appear identical to epidermal inclusion cysts, but 90% are on the scalp. There is often a family history of pilar cysts; inheritance is autosomal dominant.

Treatment of Cutaneous Cysts

  • Cyst excision or dissection, if desired

  • Milia evacuation

Troublesome cysts can be removed. To prevent recurrence, the entire cyst and its wall should be removed. Ruptured cysts can be incised and drained but may recur if the wall is not eventually removed. Antibiotics are not needed unless cellulitis Cellulitis Cellulitis is acute bacterial infection of the skin and subcutaneous tissue most often caused by streptococci or staphylococci. Symptoms and signs are pain, warmth, rapidly spreading erythema... read more Cellulitis is present.

Milia may be evacuated with a #11 blade and comedone extractor.

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