Epidermoid cysts:

  • Are round cysts or small bumps that are easy to move with your fingers
  • Are usually white or yellow, though people with darker skin may have pigmented cysts
  • Range in size from less than 1/4 inch to nearly 2 inches (a few millimeters to 5 centimeters) in diameter
  • Occur on nearly any part of your body, including your fingernails, but are found most often on your face, trunk and neck

Sometimes an epidermoid cyst has a central opening — the remnant of a hair follicle from which the cyst originally formed — that's plugged by a tiny blackhead. You may be able to squeeze out a thick, cheesy material through this opening, but because of the risk of infection and scarring, it's best to leave this to your dermatologist.

Milia — tiny, deep-seated whiteheads that never seem to come to the surface of your skin — are miniature epidermoid cysts. They're especially common in older women and in men with significant sun damage on their cheeks and temples. They can also be caused or aggravated by long-term use of oil-based creams or cosmetics.

Signs and symptoms of infection, which can occasionally occur, include:

  • A thick, yellow material draining from the cyst that may have a foul odor
  • Redness, swelling and tenderness around the cyst

A similar looking condition

Sometimes you may develop a small bump on your scalp that looks like an epidermoid cyst. These are almost always pilar or trichilemmal cysts, which usually have thicker walls than epidermoid cysts do and almost always move freely under your skin. The lining of this type of cyst differs slightly from that of an epidermoid cyst.

When to see a doctor

Most epidermoid cysts aren't harmful, but you may want to have them removed for cosmetic reasons. See your doctor if you have a cyst that:

  • Grows rapidly
  • Ruptures
  • Becomes painful
  • Occurs in a spot that's constantly irritated
Jun. 07, 2011