International Academy of Cosmetic Dermatology

KERATINOUS CYST

A keratinous cyst is the most common kind of epidermal cyst and is filled with keratin originating from the epidermis, most often from a hair follicle.  Once called a sebaceous cyst, it arises spontaneously and is prone to rupture.  It is most commonly found on the trunk, nape, and behind the ears.  When a cyst appears on the scalp, it is most commonly a trichilemmal cysts or wen.

It present as a dome-shaped, slightly mobile, elevated nodule, ranging from 0.5-5.0 cm in size.  If inflamed, it may appear red and boggy, being tender to palpation.  When drained, thick cheesy keratin debris along with purulent material can sometimes be expressed.  This is often foul smelling.

Once the surrounding sac is interrupted either by trauma or by bacterial infection, the cyst dissipates.  Thus, there can be several types of treatment:
  • Intralesional corticosteroids
  • Surgical
    • Incision and drainage
    • Complete excision
    • Cryosurgery
  • No intervention

Robert A. Norman, DO, MPH
Tampa, FL, USA

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