Cysts are common skin bumps that can occur anywhere on the body. Pilar cysts, also referred to as trichilemmal cysts or wens, are most commonly found on the scalp. The more common cyst we diagnose is called an epidermal inclusion cysts (EIC) which arises from a plugged hair follicle that forms an under the skin bump over time. Cysts occupy space under the skin and usually feel like a grain of rice or marble. Some can be as large as a plum. Cysts are benign but can become inflamed and hurt. Inflamed cysts are typically red, tender or sore and grown very big very fast and can drain. Inflamed cysts can be treated with a cortisone shot, can be drained and may sometimes need an oral antibiotic if infected.
A few lesser known types of cysts are commonly seen in the dermatologist’s office:
Pilomatricoma. Also known as a calcifying epithelioma of Malherbe or pilomatrixoma, this benign growth is typically found on the face, neck or arms. It appears as a very firm nodule and is sometimes slightly pink. It occurs more commonly in children, with girls being more frequently affected than boys. These cysts often have calcium and bony like growth in them and therefore are hard to touch. Pilomatricomas are removed by surgical excision under local anesthetic.
Milia. Milia are small cysts. They appear most frequently on the face, especially around the eyelids. They appear as very small (1-4 mm) white, firm bumps. They cannot be easily removed, and usually require a dermatologist to extract them. Milia can be caused by too vigorous exfoliation of the face, abrasive scrubs, or overly-moisturizing creams. Milia can also occur in areas where the skin has been inflamed. They can sometimes occur after cosmetic laser procedures including photodynamic therapy or laser skin resurfacing and are easily removed. Pre-treatment with a topical retinoid such as Atralin, Kinerase tretinoin, or Retin-A can ease removal.
Cysts usually appear as skin nodules, often with a central pore. Cysts are freely moveable underneath the skin and usually shiny and smooth when pressure is applied to the area of the skin. They may drain clear to bloody discharge; often pus or cheesy-material may be expressed. Inflamed cysts can be painful, red, and swollen. Inflamed cysts can be treated with dilute injected steroid. Cysts may be drained, but this is not definitive treatment. Cysts are analogous to having a water balloon under the skin—the “balloon” must be removed in order to cure the cyst. This requires a simple surgical excision completed in the office under local anesthesia.