Epidermal Cyst

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Basics ⬇

Epidermal Cyst (Also Discussed in Chapter 30: Benign Cutaneous Neoplasms)

An epidermal cyst (aka epidermal inclusion cyst or epidermoid cyst) is a well-demarcated subcutaneous nodule that typically occurs after puberty.

Clinical Manifestations ⬆ ⬇

Presents as a round, mobile, slow-growing subcutaneous nodule seen most commonly on the face, scalp, back, or scrotum.
Often a visible overlying pore or punctum through which white keratinaceous debris is extruded is typical.
Vary in size from a few millimeters to several centimeters.
Occasionally develop surrounding redness secondary to an inflammatory response to cyst wall rupture (Fig. 8.1).

Diagnosis ⬆

Diagnosis is based on clinical recognition.
A biopsy would show an epithelial lining with keratinaceous debris.

Management

If the cyst is small and asymptomatic, no treatment is necessary.
Large cysts or those that become recurrently inflamed or are in a cosmetically sensitive area may warrant excision.

Helpful Hints

Multiple epidermal cysts in childhood can be the presenting sign of Gardner syndrome, a form of familial adenomatous polyposis (FAP).
The term “sebaceous cyst” is often inaccurately used to describe epidermal cysts.
Epidermal cysts on the scalp are called pilar cysts and those on the eyelids are referred to as chalazions.