Also known as sebaceous cyst, epidermoid inclusion cyst, Infundibular cyst, epidermal cyst.
It is a benign walled-off cavity filled with keratin which originates from the hair follicle unit.
Skin-coloured to yellow-white unless inflamed. The size varies from several millimetres to centimetres.
A visible comedonal-like opening or pore (resembles a blackhead) may be seen on the surface of the papule or nodule. A soft cheese-like, sometimes malodorous, material composed primarily of keratin can usually be expressed from the opening.
Cyst contents may rupture into the dermis, eliciting an acute and chronic inflammatory reaction, leading to significant redness and pain; this inflammation is often confused with a bacterial infection
How is an epidermoid cyst diagnosed?
The diagnosis is usually made by a clinical examination. Sometimes a biopsy may be needed.
What causes an epidermoid cyst?
Most commonly sporadic. They may be primary or they may arise from disrupted follicular structures due to trauma or comedone formation (blackheads).
Multiple cysts may occur in the conjunction with acne vulgaris, Gardner syndrome and in Gorlin syndrome
How is epidermoid cyst treated?
Inflamed epidermoid cysts may require treatments with antibiotics. Incision, drainage and/or steroid injections may be helpful in rare cases to speed up the resolution of the inflammation.
Non-inflamed cysts can be removed surgically and the contents and wall of the cyst drained. However, the cyst may recur if the entire cyst wall is not removed.
- Bolognia, Jean L.; Schaffer, Julie V.; Duncan, Karynne O.; Ko, Christine J.. Dermatology Essentials E- Book (p. 880). Elsevier Health Sciences. Kindle Edition.
- The Australia college of dermatologists https://www.dermcoll.edu.au/atoz/epidermoid-cyst/
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