Excision of Epidermal Inclusion Cyst

Epidermal inclusion cysts, also called keratin or epithelial cysts, are benign lumps that develop beneath the skin. They are the most common cutaneous cysts and can be found anywhere on the body, with the face, neck, and trunk being the most common locations. Epidermal inclusion cysts are caused by a build-up of keratin due to obstruction or disruption of the skin or skin follicle. It presents as a slow-growing, painless lump, usually with a punctum in the middle that represents the blockage of keratin excretion. No treatment is usually necessary unless they cause pain, cosmetic concerns, or become infected. Surgical excision appears to be the mainstay of treatment, which prevents cyst recurrence. Here, we present the case of a 64-year-old male with a mass on his upper back. The mass was noted to be gradually enlarging, and thus excision was performed in order to prevent further growth and infection.

Epidermal inclusion cysts, otherwise known as epidermoid cysts or simply epidermal cysts, are a type of benign tumor most commonly associated with glabrous skin.¹ They are most commonly found on the face, scalp, trunk or neck regions.² Epidermal inclusion cysts are of ectodermal origin³ and are generally slow growing and appear to be surrounded by epithelial cells and composed of a keratinous mass internally.¹ The incidence of epidermal inclusion cysts is twice as high in males compared to females.⁴ Epidermal inclusion cysts are classified as either primary or secondary; primary cysts develop from the infundibulum and secondary cysts develop following the implantation of the follicular epithelium within the dermis following trauma or formation of comedones.⁴ Diagnosis of epidermal inclusion cysts is typically clinical and is determined by a cyst and can have a dark central comedone.⁵ Treatment depends on whether or not the epidermal cyst is self-resolving; if not, then surgical intervention is required.⁴

The 64-year-old male presented with an epidermal cyst on his left upper back with a punctum on the surface. The cyst had been growing for several months. There were no known allergies or contraindications.

Physical examination revealed a healthy-appearing, adult male. A soft, unilateral, palpable mass was located on the patient’s left upper back. No loss of function or range of motion was reported in this case.

If an epidermal cyst is located near a nerve, vessel, bone, breast tissue, or in intracranial locations, MRI or CT imaging should be done.² Epidermal cysts have the potential to compress nerves and cause spasms⁶, which is why caution should be taken when excising masses from the areas noted above.

The pathophysiology of epidermal cysts varies. The majority of epidermal cysts originate from the follicular infundibulum below the skin⁵. As stated in the video, epidermal cysts can return after excision if a portion of the fibrous capsule is not removed during the surgery.

If the cyst is small, uncomplicated, and can be kept clean, treatment is not necessary.⁵ Surgical incision before the cyst becomes infected may prove beneficial as the surgical planes may be less evident should the cyst become infected.⁷ Patients may, however, request the excision of cysts for aesthetic reasons. If the epidermal cyst is to be removed, surgical excision is preferred to minimize risk of recurrence of a second cyst in the future.

Minor epidermal cysts without symptoms can be left untreated. If the cyst becomes infected or inflamed, or if the patient prefers excision for cosmetic purposes, surgical excision is warranted.

No special considerations were considered for this patient.

The procedure started with cleaning the superficial region containing the cyst and injecting 2% Xylocaine to the area around the epidermal cyst while the patient lay prone. A local anesthetic will spray out of the cyst during injection if the needle crosses the cyst wall and is injected into the cyst core. A transverse, elliptical incision was made inferiorly and superiorly to the cyst, and extended roughly 2 cm laterally to the cyst. The corners of the elliptical incision are where the cyst was released from. Clamping the corners allows the surgeon to avoid puncturing the cyst wall, which will help prevent recurrence. Once the incisions have been made, and the cyst wall is identified, a scalpel can be used to dissect the tumor out. After removal, internal and external sutures were used to close off the wound. Due to the depth, internal sutures were required to stabilize the wound and prevent infection. An inverted-T suture technique with absorbable sutures was utilized with the internal suture. Non-absorbable sutures were used on the external suture.

As shown in the video, the patient was able to be discharged the same day as the procedure. There was no medical history that warranted concern for post-operative bleeding. The post-op instructions included cleaning the wound, changing the gauzes daily, and returning in one week after the surgery to remove the external sutures. Prognosis for superficial cysts such as the one in the video are excellent as they typically relieve themselves. In the rural medical setting where there are physician shortages, procedures like these can be utilized at low cost to prevent infection and improve quality of life to patients who may have to wait months to years for elective procedures.

No specialized equipment was used in this case.

Nothing to disclose.

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.