|Classification and external resources|
A sebaceous cyst (pron.: / /) is a term that loosely refers to either epidermoid cysts (also known as epidermal cysts; L72.0) or pilar cysts (also known as trichilemmal cysts; L72.1). Because an epidermoid cyst originates in the epidermis and a pilar cyst originates from hair follicles, by definition, neither type of cyst is strictly a sebaceous cyst. The name is regarded as a misnomer as the fatty, white, semi-solid material in both of these cyst entities is not sebum, but keratin. Furthermore, under the microscope neither entity contains sebaceous glands. In practice, however, the terms are often used interchangeably.
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The scalp, ears, back, face, and upper arm, are common sites for sebaceous cysts, though they may occur anywhere on the body except the palms of the hands and soles of the feet. In males a common place for them to develop is the scrotum and chest. They are more common in hairier areas, where in cases of long duration they could result in hair loss on the skin surface immediately above the cyst. They are smooth to the touch, vary in size, and are generally round in shape.
They are generally mobile masses that can consist of:
- Fibrous tissues and fluids,
- A fatty (keratinous) substance that resembles cottage cheese, in which case the cyst may be called "keratin cyst" This material has a characteristic "cheesy" or "foot odor" smell,
- A somewhat viscous, serosanguineous fluid (containing purulent and bloody material).
The nature of the contents of a sebaceous cyst, and of its surrounding capsule, will be determined by whether the cyst has ever been infected.
With surgery, a cyst can usually be excised in its entirety. Poor surgical technique or previous infection leading to scarring and tethering of the cyst to the surrounding tissue may lead to rupture during excision and removal. A completely removed cyst will not recur, though if the patient has a predisposition to cyst formation, further cysts may develop in the same general area.
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Sebaceous cysts generally do not require medical treatment. However, if they continue to grow, they may become unsightly, painful, infected, or all of the above.
There are three general approaches used: traditional wide excision, minimal excision, and punch biopsy excision.
The typical outpatient surgical procedure for cyst removal is to numb the area around the cyst with a local anaesthetic, then to use a scalpel to open the lesion with either a single cut down the center of the swelling, or an oval cut on both sides of the centerpoint. If the cyst is small, it may be lanced instead. The person performing the surgery will squeeze out the keratin surrounding the cyst, then use blunt-headed scissors or another instrument to hold the incision wide open while using fingers or forceps to try to remove the cyst intact. If the cyst can be removed in one piece, the "cure rate" is 100%. If, however, it is fragmented and cannot be entirely recovered, the operator may use curettage (scraping) to remove the remaining exposed fragments, then burn them with an electro-cauterization tool, in an effort to destroy them in place. In such cases the cyst may recur. In either case, the incision is then disinfected and, if necessary, the skin is stitched back together over it. A scar will most likely result. In some cases where "cure rate" is not 100% the resulting hole is filled with an antiseptic ribbon after washing it with an iodine based solution. This is then covered with a field dressing. The ribbon and the dressing are to be changed once or twice daily for 7–10 days after which the incision is sewn up or allowed to close by secondary intention, i.e. by forming granulation tissue and healing "from the bottom up."
An infected cyst may require oral antibiotics or other treatment before or after excision.
An approach involving incision, rather than excision, has also been proposed.
See also 
|Wikimedia Commons has media related to: Sebaceous cysts|
- "Epidermoid and Pilar Cysts (Sebaceous Cysts) - Patient UK". Retrieved 2013-03-04.
- "Cysts - Epidermoid and Pilar - British Association of Dermatologists". November 2010. Retrieved 2011-07-04.
- MedlinePlus Encyclopedia Sebaceous cyst
- Zuber TJ (2002). "Minimal excision technique for epidermoid (sebaceous) cysts". Am Fam Physician 65 (7): 1409–12, 1417–8, 1420. PMID 11996426.
- Harbin LJ, Khan M, Thompson EM, Goldin RD (2002). "A sebaceous cyst with a difference: Dermatobia hominis". J. Clin. Pathol. 55 (10): 798–9. doi:10.1136/jcp.55.10.798. PMC 1769786. PMID 12354816.
- Klin B, Ashkenazi H (1990). "Sebaceous cyst excision with minimal surgery". American Family Physician 41 (6): 1746–8. PMID 2349906.
- Moore RB, Fagan EB, Hulkower S, Skolnik DC, O'Sullivan G (2007). "Clinical inquiries. What's the best treatment for sebaceous cysts?". The Journal of family practice 56 (4): 315–6. PMID 17403333.
- Nakamura M (2001). "Treating a sebaceous cyst: an incisional technique". Aesthetic plastic surgery 25 (1): 52–6. doi:10.1007/s002660010095. PMID 11322399.
- Overview at University of Maryland Medical Center
- Epidermal Inclusion Cyst at eMedicine
- Sebaceous Cyst (Epidermal Cyst) - Pictures, Causes, Treatment and Removal - PrimeHealthChannel.com