Summary about Disease
An epidermal inclusion cyst (sometimes called an epidermoid cyst, sebaceous cyst, or keratin cyst, although "sebaceous cyst" is technically inaccurate) is a benign, slow-growing, mobile, firm, and usually painless nodule in the skin. It is formed when epidermal cells, which normally exfoliate, get trapped beneath the skin's surface. These cells form the wall of the cyst and then secrete keratin, a protein that makes up skin, hair, and nails, into the interior of the cyst.
Symptoms
Small, round bump under the skin.
Usually flesh-colored, white, or yellowish.
May have a small central pore (punctum) that may be visible as a dark spot.
Usually painless, but can become tender, inflamed, or infected.
May produce a thick, cheesy, foul-smelling discharge if ruptured.
Can vary in size from a few millimeters to several centimeters.
Causes
Trapped epidermal cells: The most common cause is the trapping of epidermal cells beneath the skin, often due to hair follicles, injury, or surgical procedures.
Blocked hair follicles.
Damage to the skin's surface.
Human papillomavirus (HPV) infection (rare).
Genetic predisposition (rare, as in Gardner's syndrome).
Medicine Used
No specific medicine is used to directly treat the cyst itself.
Topical or oral antibiotics: Prescribed if the cyst becomes infected. Common antibiotics might include cephalexin, dicloxacillin, or clindamycin.
Steroid injections: Sometimes injected into inflamed cysts to reduce swelling and tenderness.
Pain relievers: Over-the-counter pain relievers like ibuprofen or acetaminophen can help manage discomfort.
Is Communicable
No, epidermal inclusion cysts are not communicable. They are not caused by a contagious agent.
Precautions
Avoid squeezing or picking at the cyst: This can lead to inflammation, infection, and scarring.
Keep the area clean: Gently wash the area around the cyst with soap and water.
Apply a warm compress: This can help reduce inflammation and promote drainage if the cyst ruptures.
Seek medical attention if the cyst becomes inflamed, painful, or shows signs of infection: Redness, swelling, warmth, and pus are signs of infection.
If you are prone to cysts in areas you shave, use good technique and proper skin hydration.
How long does an outbreak last?
An epidermal inclusion cyst is not an "outbreak" in the traditional sense. It is a growth. Once formed, a cyst can persist indefinitely unless treated or removed. Inflammation or infection can occur intermittently, and each episode may last for several days to weeks.
How is it diagnosed?
Physical examination: The doctor will examine the cyst and the surrounding skin.
Medical history: The doctor will ask about your medical history and any previous skin problems.
Incisional Biopsy or Excision with Histopathology: Seldom is a biospy or excisional biospy warranted in the diagnosis of an epidermal inclusion cyst. It is more commonly needed when a cyst is suspected to be something more nefarious.
Timeline of Symptoms
The timeline can vary:
Formation: A small, often unnoticed bump develops gradually under the skin. This can take weeks, months, or even years.
Growth: The cyst slowly increases in size over time.
Inflammation/Infection (optional): At any point, the cyst may become inflamed or infected, causing pain, redness, swelling, and potential drainage.
Rupture (optional): The cyst can rupture, releasing a foul-smelling, cheesy substance. This may relieve pressure but can also lead to further inflammation or infection if not kept clean.
Persistence: Without treatment, the cyst remains until it is surgically removed or spontaneously resolves (rare).
Important Considerations
Self-diagnosis is not recommended. Always consult a healthcare professional for proper diagnosis.
Surgical removal is the most effective treatment. This involves completely excising the cyst wall to prevent recurrence.
Incision and drainage is a simpler procedure, but recurrence is common.
Rule out other conditions: A doctor needs to differentiate the cyst from other skin lesions, such as lipomas, abscesses, or other types of cysts.
Gardner's syndrome: Multiple epidermal inclusion cysts can be a sign of Gardner's syndrome, a rare genetic disorder, requiring further evaluation.