What is Dermoid Cyst?

A dermoid cyst is a harmless skin anomaly that forms when skin tissues get trapped in the wrong place during early development. These cysts are lined by a type of tissue similar to the outer layer of the skin and can have mature skin parts on their walls. Their interiors are filled with material similar to that of skin and hair. Dermoid cysts are present from birth, but not all are recognized at that time. In fact, only 40% of these cysts are found at birth, while 60% of them are discovered by the age of five. Dermoid cysts often appear within the first year of life and grow slowly over time. They are found most commonly on the head and neck, with 84% of these cysts occurring in this region.

What Causes Dermoid Cyst?

The exact cause of dermoid cysts is still a mystery. Dermoid cysts are a type of congenital birth defect, meaning they occur while a baby is still in the womb. These cysts originate when skin and skin structures get enveloped within the body during fetal development.

An important aspect to understand is that dermoid cysts are considered ‘true hamartomas.’ Essentially, hamartomas are benign growths that are made up of normal tissues but organized in an irregular way.

In terms of who gets these cysts, studies have shown no direct link between the location of the cyst and the person’s sex, age, or their tissue’s microscopic structure.

Risk Factors and Frequency for Dermoid Cyst

Dermoid cysts, which are among the most common tumors found in the skulls of children, represent a significant portion of all scalp and skull growths in young patients. These cysts are typically present from birth and are most often discovered in children five years old or younger. However, there have been instances where these cysts were discovered in adults. Although they tend to occur slightly more in girls, no strong gender preference exists. Also, there’s no racial bias towards the occurrence of these cysts, but they are most commonly reported in the white population.

Dermoid cysts are some of the most common skull tumors in children.
They represent 15.4%-58.5% of all scalp and skull growths in young patients.
Usually, dermoid cysts are detected in children five years old or younger.
There are also instances where the cysts are discovered in adults.
These cysts tend to occur slightly more in girls.
No significant racial difference is present in the occurrence of dermoid cysts, but most reports come from the white population.

Signs and Symptoms of Dermoid Cyst

Dermoid cysts typically occur in the head and neck area, but can be found anywhere on the body. Some of the most common locations in the head and neck area include the forehead, the back of the head, and the area above the eye orbit, particularly around the outer part of the eyebrow. Sometimes, an eyelid dermoid cyst might be noticed as a non-painful bump on the upper eyelid that doesn’t move freely.

On the lower eyelid, a dermoid cyst might present as a painless swelling that grows slowly. In the inner corner of the eye (the medial canthal area), dermoid cysts may appear as lumps attached to the tear ducts.

While a person usually has only one dermoid cyst, cases of multiple cysts have been reported. These cysts usually appear as:

Pale, flesh-colored, shiny nodules
Dome-shaped and firm to the touch
Located deep in the skin
Usually without symptoms, not throbbing, and cannot be compressed

Sometimes, there may be hair visible at the opening of the dermoid cyst. This is a clear sign of a dermoid cyst. It’s also worth noting that a cyst located on the middle of the body might look like a pit seeping oily material that can occasionally get inflamed or infected.

Testing for Dermoid Cyst

Dermoid cysts can grow over time and may even extend into the brain or spinal cord. Because of this, it’s often recommended to carry out some kind of imaging test, like an X-ray or MRI, especially if the cyst is located in the middle of the body or on the scalp. This helps to understand the cyst better before performing any procedures like a biopsy. The issue with biopsies or draining the cyst is that it could lead to an infection, which can result in conditions like bone infection (osteomyelitis), meningitis, or a brain abscess. Other possible complications from dermoid cysts include bone erosion, eyelid displacement, and the cyst extending into the cranium.

Cysts located centrally in the body (midline dermoid cysts) are more likely to be associated with malformations of the brain or spine, or extend into the cranium. Interestingly, dermoid cysts found in the nose are the most common nose malformation present from birth. Studies have found that slightly more than 1 in 10 patients with a nasal dermoid cyst may also have the cyst extend into their brains. When it comes to imaging tests, MRI is the best way to spot any extensions of the cyst into the brain or spinal cord.

Studies have also noted a higher correlation between dermoid cysts located in the forehead and pterional (the region where the temple is located) regions with bone erosion. In such cases, a CT scan is preferred to clearly identify these bone changes. High-resolution ultrasounds might also be beneficial in some cases to spot any deep components of the cyst. Under ultrasound, dermoid cysts appear as a well-defined homogenous and hypoechoic (dark on ultrasound imaging) cystic lesion.

Moreover, in some cases, if there’s a suspicion of deep involvement of the cyst, a procedure termed ‘Fistulography’ might be done before surgery. In atypical cases, another procedure known as ‘Dacryocystography’ might be performed. Because the possible complications for a dermoid cyst can involve the brain or spinal cord, it’s highly recommended for those with complicated cysts to consult with a neurosurgeon.

Treatment Options for Dermoid Cyst

Dermoid cysts often grow at a slow pace and can possibly lead to bone deformity, or extensions into the brain or spinal area. If these extensions do occur, they can result in severe infections like meningitis or even create an abscess. There are instances where a small, symptom-free dermoid cyst may not need immediate removal as it can remain stable or even shrink over many years. But because it’s common for these cysts to grow larger with time, it’s generally recommended to have them surgically removed by an experienced surgeon before complications arise, such as deformities or infections.

Surgery done early, besides preventing serious complications, can also make for a less invasive operation and smaller scar, which improves the cosmetic result. Another advantage of surgical removal involves obtaining a tissue sample for diagnosis. This is important because if there is a rare case where the lump turns out to be malignant, it would be initially mistaken for a benign cyst.

The preferred way to remove most dermoid cysts is a direct approach, delicately separating the cyst from the bone to which it has attached. If the cyst breaks open during surgery, any leftover tissue should be carefully removed using scraping techniques and thorough rinsing.

In instances where the cyst has stuck to vital structures, it may only be possible to remove part of it. It’s been observed that cysts can reappear if not entirely removed. Prior removal decreases the likelihood of cyst rupture, which in turn reduces the chance of the cyst recurring. Endoscopic surgery, a less invasive procedure using a small camera, can be used to remove small dermoid cysts. However, if the cyst has grown into the brain, a more traditional brain surgery may be needed.

Dermoid cysts are not very common, and they’re one disease that doctors might consider when they see a patient with a lump underneath the skin, particularly in the head, neck, or middle part of the body. They are considered when evaluating the patient’s situation. Below are other diseases that may look like a dermoid cyst:

Epidermoid cyst
Glioma
Encephalocele
Juvenile xanthogranuloma
Lipoma
Pilar cysts
Meningioma
Neurofibroma
Teratoma
Rhabdomyosarcoma
Olfactory neuroblastoma
Lymphoma
Abscess under the skin
Facial injury
Trichilemmal cyst
Pilomatrixoma
Lymphatic malformation
Thyroglossal duct cyst

The correct diagnosis among these possibilities can be determined through proper and thorough examination and testing.

What to expect with Dermoid Cyst

Generally, patients with a dermoid cyst have a good chance of recovery, especially if the cyst has not spread to the brain or spine. Although these cysts are not cancerous, they may grow and damage the skull, potentially extending into the area around the spinal cord.

Even for patients whose cyst has spread to the brain or the spinal cord, their outlook is still positive, assuming they get surgery in a timely manner. In rare cases, though, a dermoid cyst can cause symptoms due to its size, if it bursts, becomes infected, or even compresses the brain. In such situations, the prognosis can be poor.

Possible Complications When Diagnosed with Dermoid Cyst

Dermoid cysts that do not extend into the brain or spinal cord generally do not have any complications. However, if they do extend into these areas, they may lead to serious conditions such as meningitis (inflammation of the membranes surrounding the brain and spinal cord), an abscess (a confined pocket of infection), or a local mass effect (pressure from the cyst causing damage to nearby tissues).

Performing tests like aspiration (sucking out the fluid with a needle) and biopsies (removing a small sample of the cyst for testing) can sometimes lead to infection. If this infection spreads, it can cause severe conditions like osteomyelitis (infection of the bone), meningitis, or a cerebral abscess (a collection of infected material within the brain).

Other possible complications can include:

Bony erosions (deterioration of the bone)
Eyelid displacement (moving of the eyelid from its normal position)
Intracranial extension (the cyst spreading into the brain)

A very rare complication of long-standing dermoid cysts is malignant transformation, where the cyst turns into cancer. This transformation into squamous cell carcinoma (a common type of skin cancer), has been described in dermoid cysts located in the area under the tongue, the ovaries, and within the abdominal cavity.

Preventing Dermoid Cyst

A dermoid cyst is a harmless skin abnormality, commonly found in the head and neck areas of children. Given its capacity to grow and potentially cause complications, it is suggested that such conditions be addressed with early surgical treatment.