One of the more common lumps I see in new patients is something called a dermoid cyst. Very often these are found near or underneath the outer part of the eyebrow and feel like a rubbery pea-shaped lump underneath the skin. These particular dermoid cysts are often called angular dermoids, or peri-orbital dermoids.
They are usually first noticed when the baby is a few weeks old and generally grow quite slowly within the first year or so of life.
Although they are usually found near the outer eyebrow, they can also occur between the eyebrows and elsewhere over the face and head. They can also occur elsewhere in the body, but this article will concentrate on the ones in the face.
So what causes a dermoid cyst?
Dermoid cysts occur when collections of cells that make tissues such as hair and skin, form underneath the skin in the wrong place. They often occur near the small joints between bones, such as near the joint between the bone of the forehead and the bone that makes up the side of your eye socket. These cells can continue to grow, and as a result, the lump will slowly increase in time.
Are dermoid cysts dangerous?
Dermoid cysts don’t usually cause any problems, and if left alone, will slowly increase in size. Your baby will not usually notice them as they do not usually cause any symptoms, although they can press on surrounding structures if they become very large.
These cysts have been known to become infected which then requires treatment with antibiotics and sometimes surgery.
Can they be removed?
As there is a risk of infection, and because these lumps tend to slowly get bigger with time, most parents choose to have them removed.
The best approach to remove the dermoid cyst will depend very much on a number of factors, including, the exact location and how mobile it is. With the dermoid cysts which are closer to the eye, I like to use an incision which passes along the fine crease in the upper eyelid. This usually results in an excellent scar which is well hidden in the eyelid crease. These little scars heal up quickly and are really a good approach for many of angular dermoid cysts.
When the dermoid is slightly further away from the eye, then I find that either an endoscopic or keyhole technique enables me to remove these cysts through small incisions just behind the hairline. Although this is technically more challenging, it means that I can avoid placing a scar above or near the eyebrow.
There are some cysts which are best suited to a direct approach, and with a lot of care and some delicate suturing, often these incisions will heal well with a very acceptable cosmetic result.
What about a dermoid cyst between the eyebrows?
These ‘midline dermoids’ are more commonly associated with a connection which can pass through the forehead or nasal bones into the head. If your baby has a dermoid cyst in this location, I would generally request an MRI or CT scan to assess for this possibility.
If the scan does show that there is a connection to a part of the dermoid cyst inside the head then I would always work together with a neurosurgeon to safely remove the part of the cyst on the face as well as that inside the head and the connection between.
What is the best age for my baby to have dermoid cyst surgery?
As many of these lesions, grow very slowly, I would generally recommend that any surgery is carried out after the first year of life when babies are a little bigger and stronger. Although most of my patients are between the ages of 1 and 2, surgery to remove these cysts can be performed at almost any age
Can the cyst come back?
There is a small chance that the cyst may reform. This is more likely if the cyst is ruptured during surgery or if there has been an episode of infection in the past.
During surgery, being meticulously careful to tease away the cyst from the normal surrounding tissue is the best way to reduce the chance of recurrence.
However, if the cyst does recur, surgery is often curative.
What are the risks of surgery?
The vast majority of dermoid cysts can be removed as day case procedures under a short general anaesthetic. The surgery usually takes less than an hour and children are often back to their normal selves within a day or two.
Surgery for the more unusual intracranial dermoid cysts will take about 4 hours, and your child will need to stay in hospital for a few days.
There will be a scar, which although may be very fine, is permanent. The exact location of this scar will vary between patients.
As with any type of surgery, there is a small risk of a wound infection, and antibiotics will be used to reduce this risk during the operation.
I may prescribe a week of antibiotics in some cases, such as if there is a deeper part, such as an intracranial part, or a history of infection or the cyst has a connection called a punctum to the surface of the skin.
All small children will require a general anaesthetic to enable me to remove the cysts carefully and completely in the best way possible.