A periorbital dermoid cyst is a common, non-cancerous growth found near the eye. It is classified as a benign congenital choristoma, meaning it is a mass of normal tissue located in an abnormal area. Although these growths are present at birth, they often become noticeable later in childhood. The cyst contains trapped skin elements that slowly accumulate, causing the mass to enlarge over time.
How Periorbital Dermoid Cysts Form and Where They Are Located
These cysts originate during the earliest stages of fetal development. They form when the ectoderm, the tissue layer that forms the skin and nervous system, is folding and fusing. A dermoid cyst occurs when surface skin cells become trapped beneath deeper layers as embryonic facial structures close along the skull’s suture lines. This explains their frequent location near the junctions of the bones forming the eye socket.
The term “periorbital” specifies the location around the orbit, or eye socket, where most dermoid cysts on the head and neck are found. The most frequent location is the superolateral aspect of the orbit, appearing near the outer edge of the eyebrow at the frontozygomatic suture. Less commonly, they form medially, closer to the nose-eye junction, near the frontoethmoidal or frontolacrimal sutures.
The cyst is a sac lined with squamous epithelium, the same tissue that makes up the outer layer of skin. This trapped tissue functions like normal skin, shedding old cells and producing secretions like oil and sweat. As these materials accumulate within the enclosed sac, the cyst slowly grows, often containing greasy, yellow material, hair follicles, and other skin structures. Some orbital dermoids are “dumbbell-shaped,” with one part visible under the skin and a deeper lobe extending into the bone or eye socket.
Identifying Symptoms and Confirming Diagnosis
A periorbital dermoid cyst presents as a smooth, firm, and movable lump located just beneath the skin. The mass is painless and is often first noticed in infancy or early childhood, though it may grow slowly over many years. The overlying skin appears normal, without redness or inflammation, unless the cyst has ruptured or become infected.
If the cyst grows large enough, especially in deeper locations, it can cause secondary issues like a drooping eyelid or, rarely, visual changes due to pressure on the eyeball. A sudden impact can cause the cyst wall to rupture, releasing contents into the surrounding tissue. This leads to a significant inflammatory reaction, pain, and swelling. Physicians diagnose the cyst primarily through clinical examination, palpating the lump to assess its size, mobility, and tenderness.
Imaging studies are necessary to confirm the diagnosis and plan for removal, and to rule out other possible masses. A Computed Tomography (CT) scan or Magnetic Resonance Imaging (MRI) determines the cyst’s exact depth and its relationship to the underlying bone and eye socket contents. This imaging is important to ensure the mass is not connected to the brain or sinuses, which would complicate surgery. Scans can also reveal if the cyst has caused any remodeling of the adjacent bone, a common finding with these slowly expanding lesions.
Surgical Removal
Surgical excision is the standard and most effective treatment for a periorbital dermoid cyst. The primary goal is the complete removal of the entire cyst sac, or capsule, to prevent recurrence. This surgery is performed under general anesthesia, especially in younger patients, and often takes place on an outpatient basis.
The surgeon must carefully dissect the cyst from surrounding tissues, taking care to remove the sac intact without rupturing it. If the cyst contents leak during the operation, the resulting inflammatory reaction can complicate healing and increase the risk of recurrence. If a rupture occurs, copious irrigation with saline solution is performed to wash away the irritating contents and minimize the local tissue response.
Various incision approaches are utilized to achieve complete removal and an optimal cosmetic outcome, a significant consideration in the visible periorbital region. Incisions may be placed directly over the mass, within the eyebrow hair, or along a natural crease line of the upper eyelid to hide the resulting scar. Operating here requires meticulous technique due to the proximity of delicate structures like the orbit, eye muscles, and branches of the facial nerve.
For deeply embedded or “dumbbell-shaped” cysts, the surgery requires a more complex approach to ensure the deep portion is entirely excised. Although rare, potential intraoperative risks include injury to the facial nerve, which could cause temporary or permanent weakness of the eyelid or brow muscles. Achieving a clean, complete excision is paramount, as residual epithelial cells can lead to the formation of a new cyst.
Recovery and Long-Term Outlook
Following surgical removal, proper post-operative care ensures a smooth recovery and an aesthetically pleasing result. Patients may experience mild pain and swelling at the incision site, which is managed effectively with over-the-counter pain medication. Applying a cold compress or ice pack to the area for the first 48 hours helps minimize swelling and discomfort.
The incision is closed with fine stitches, which may be dissolving or removed by the physician within 5 to 10 days after the procedure. Wound care involves keeping the site clean and dry, often using a prescribed antibiotic ointment to prevent infection. Most children return to school and light activities within about five days, though strenuous activities or swimming are restricted for one to two weeks.
The long-term prognosis after complete surgical removal of a periorbital dermoid cyst is positive. If the entire cyst capsule is successfully excised, the risk of recurrence is very low. While a small scar remains from the incision, surgeons place the cut along natural skin lines, resulting in a scar that typically fades significantly over time.