Dermoid Eye Cyst - Causes, Risk Factors, Diagnosis and Treatment

What Is Dermoid Eye Cyst?

A dermoid cyst of the eye is congenital (since birth) choristoma. Choristomas are tumor-like growth of normal cells in an abnormal location. Dermoid cysts are structures originating from ectoderm like hair follicles, keratin, sweat, and sebaceous glands. More than eighty percent of the dermoid cysts occur in the head and neck region, out of which dermoid cysts of the eye are the most common. The dermoid cysts of the eyes include orbital, conjunctival, and corneal cysts. Most common among them are the orbital dermoid cysts, whereas conjunctival and corneal cysts are uncommon.

What Causes Dermoid Eye Cyst?

Sequestration (inclusion) of epithelium embryologically is the leading cause of dermoid eye cysts. In addition, there is entrapment of epithelial cells during the closure of frontomaxillary, frontotemporal and frontozygomatic sutures.

The three significant dermoid eye cysts differ in their epithelium lining and internal structure. The different types of dermoid cysts are:

1. Orbital Cyst: In orbital cysts, sequestration of the squamous epithelium occurs. It is a cystic lesion.

2. Conjunctival Cyst: It is lined by conjunctival epithelium containing goblet cells. It is a solid tumor.

3. Corneal Cyst: It is lined by squamous epithelium and has ectodermal and mesodermal structures (from mesoderms like blood vessels, fat cells, and cartilage) components. It is a solid tumor.

What Are the Clinical Features of Dermoid Eye Cyst?

All three cysts show changes in their site of appearance, time of occurrence, and specific signs and symptoms.

Following are the clinical features of the different types of dermoid eye cyst:

• Orbital - It becomes apparent only in the first decade of life. It is mostly asymptomatic, but there may be diplopia if it is present inside the orbit. They are slow-growing, painless, firm masses present in the lateral aspect of the eyebrow and fixed to the underlying bone. An orbital dermoid cyst may sometimes leak material into the surroundings resulting in inflammatory reactions.

• Conjunctival - These tumors begin at birth but only appear in the 40s. The tumor is a soft, fluctuant subcutaneous mass. It is present in the superonasal aspect of the orbit.

• Corneal - They present clinically as white or yellowish, solid, smooth surface mass protruding from the eyeball. Corneal cysts are primarily located in the corneal region. Sometimes, corneal cysts are so large that they prevent the expected closing of the eye.

Some of the typical clinical signs which may appear in patients suffering from all the three types of dermoid cysts of the eye include:

1. Palpable mass.

2. Ptosis (drooping of the upper eyelid).

3. Proptosis (bulging eyes).

4. Strabismus (cross eyes).

5. Pulsating proptosis with mastication.

6. Globe displacement.

7. Restriction in extraocular movements.

8. inflammation.

9. Orbitocutaneous fistula.

What Are the Different Clinical Forms of Dermoid Eye Cysts?

The orbital and corneal dermoid cysts occur in various forms clinically.

1. Orbital Dermoid Cyst:

Based on the depth of invasion:

• Superficial - Present as a smooth, painless mass in superotemporal and are more common. It can be mobile or fixed to the underlying bone.

• Deep - Deep cysts may remain occult and appear only in adulthood. When they enlarge, they might produce ptosis, strabismus, and diplopia.

Based on the size of the tumor:

• Small - These cysts are mostly asymptomatic and regress by themselves.

• Large - These larger cysts might sometimes displace the globe.

Based on the location of the suture to the surrounding bone and soft tissue:

• Juxtasutural - The cyst is present near the sutural lines.

• Sutural - The cyst is present on the suture.

• Soft Tissue - The tissue is present on the soft tissue.

Based on the type of growth:

• Exophytic - Exophytic dermoid cysts grow externally.

• Endophytic - Endophytic dermoid cysts grow internally.

2. Corneal Cysts:

Based on their severity of clinical presentation:

• First Grade of Severity - These cysts are present only on the superficial layers of the limbus and cornea.

• Second Grade of Severity - These cysts cover the cornea fully.

• Third Grade of Severity - They are large dome-like cysts plunging between the eyelids.

What Are the Risks and Syndromes Associated With a Dermoid Eye Cyst?

The dermoid cysts of the eye pose several risks to the patient depending upon their size and extent.

• The orbital dermoid cyst may sometimes penetrate the frontal sinus by passing through the roof of the orbit.

• In the case of a large cyst, part of the cyst is in orbit, and the other part is in the temporal fossa connected by a defective bone known as the dumbbell orbital cyst.

• The orbital dermoid cysts can form fistulas with the adjacent skin of the cyst and drain the contents of the cyst into the fistula.

• Leakage of the cystic content into the surrounding lesion elicits a primary inflammation.

• Corneal cysts are associated with Goldenhar-Gorlin syndromes (congenital syndrome affecting the bones of the face).

How Can We Diagnose Dermoid Eye Cyst?

It can be easily detected by clinical examination. However, radiographic diagnostic procedures also play a vital role in the cyst's confirmatory diagnosis. These include:

• Computed Tomography (CT): It is mainly used to assess the bony changes occurring inside the cyst and the bone's rims and margins. It also helps recognize dumbbell cysts (cysts that have their contents on both sides of bone with communication between them). CT shows a non-enhancing lesion with smooth margins. Conjunctival cysts do not display any abnormal findings in CT if it is not in contact with the bone.

• Magnetic Resonance Imaging (MRI): They help appreciate the size and shape of the cyst with the fat suppression technique.

What Is the Need for Treating Dermoid Cyst Tumors of the Eye?

The removal of dermoid cysts of the eye may minimize the cosmetic compromise and risk of amblyopia and recurrent inflammation linked with the cysts.

Can Dermoid Eye Cysts Be Treated?

For all cysts, the treatment of choice is surgical excision. However, the mode of treatment for a particular cyst depends upon the cyst size that might include the following:

• A small cyst with no symptoms does not require any treatment. They may regress spontaneously.

• Surgical excision with the lining intact is ideal for removing a large cyst.

• The cyst's contents should be drained first for a considerably large cyst, followed by surgical excision.

Are There Any Other Tumors Which Mimic Dermoid Eye Cyst?

• Orbital Epidermoid Cyst: They are lined by squamous epithelium but lack the presence of hair and sebaceous glands inside the cavity.

• Orbital Mucocele: Orbital mucoceles occur primarily in adults, and often patients have a history of trauma.

• Orbital Dermolipoma: It is a benign fat tumor of the eye present in the conjunctiva.

• Lacrimal Tumors: Benign tumors occurring in the lacrimal gland.

Does Dermoid Eye Cyst Have Good Prognosis?

Orbital dermoid cysts have a good prognosis. Surgical excision does not cause further complications and exhibits very few recurrence rates.

What Are the Drawbacks of Surgery Excision of Dermoid Eye Cyst?

Surgical excision of the dermoid eye cyst can cause a few post-surgical complications. Some of these complications include -

• Spillage of the cystic contents during the surgery can initiate a granulomatous inflammatory reaction.

• After surgery, the occurrence of ecchymosis (discoloration in the skin due to bleeding beneath the skin post-trauma).

• Incomplete removal of the cyst leads to recurrence of the cyst.

• Formation of orbitocutaneous fistula due to the presence of residual dermoid tissue after removing the cyst.

Conclusion:

Dermoid eye cysts are benign eye tumors. They originate from the ectodermal germ layer due to the inclusion of epithelium during fetal development. They are diagnosed both clinically and radiographically. Clinically, they appear as smooth, painless masses. Dermoid cysts are cured surgically with a minimal recurrence rate. It is essential to seek the advice of a healthcare provider if you experience any of the symptoms of a dermoid eye cyst.