Cysts

By Michael Warren, PA-C

Epidermal cysts are visible lesions that can arise anywhere on the skin and are very common. Typically they can be asymptomatic, but they can also become inflamed, rapidly expand, or rupture. Cysts are usually solitary and frequently develop in areas of friction. They can feel like firm, dome-shaped intradermal or subcutaneous nodules ranging from 0.5 to 5 cm in size. They can feel somewhat mobile in or under the skin but are tethered to the overlying skin through a pore that often appears as a comedone. Cysts are typically filled with sterile, purulent material and keratin debris.

If a cyst becomes inflamed they will feel warm, red and boggy, and tender to the touch. The material inside the cyst typically drains toward the surface of the skin through the involved pore, however the cyst may rupture in the skin causing the cyst to appear like a bacterial infection. Subsequently if cultured, cysts usually contain normal skin flora. Once the inflammation subsides on an inflamed cyst they will more often then not recur unless the inflammatory response is brisk enough to destroy the cyst wall. Scarring around the cyst often follows this process regardless.

If a cyst ruptures or become severely inflamed they should be incised and drained under local anesthesia, but this does not always completely clear the cyst even with curetting of the cyst lining. Ultimately, surgical excision of a cyst must be weighed against the possibility of scaring from a rupture of the cyst. Cysts become more difficult to remove after they have ruptured and the subsequent resulting surgical scar may become much larger due to this. If a cyst is symptomatic or recurrent it should be surgically removed. During removal all attempts are made to get the entire cyst lining so that nothing is left to regrow the cyst. Cysts typically can be removed under local anesthesia in clinic.