What Are Dermoid Cysts?
Oral dermoid cysts are developmental cysts usually lined by epidermis-like epithelium. They may also contain dermal or adnexal structures ranging from sebaceous glands, hair follicles, or certain sweat glands within the cystic walls. These cysts are non-cancerous growths from versatile stem cells and develop into skin-related structures. Dermoid cysts are usually thin-walled (2 to 6 mm thick) and often contain a yellowish, oily material.
Dermoid cysts are traditionally classified in medicine as benign teratomas or cystic teratomas. However, research indicates that these cysts do not contain tissue from all three germ layers (as in the case of a true teratoma), so they cannot be considered teratomas.
According to statistical data on dermoid cysts, 34 percent are found in the head and neck region, and 6.5 percent are commonly located in or around the floor of the mouth. Atypical dermoid cysts mainly occur in the midline or the anterior portions of the oral cavity and tend to manifest later in the second or third decade of life.
What Is the Etiology of Dermoid Cysts?
According to the origin, dermoid cysts can be of two types -
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Congenital Dermoid Cyst - The congenital dermoid cyst is most commonly located within the cervicofacial region. It is caused by the entrapment of remnants of epithelial cells during midline fusion in embryonic development. Another major hypothesis for dermoid cysts is the congenital entrapment of ectodermal tissue, specifically during midline closure of the first and second branchial arches.
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Acquired Dermoid Cysts - Acquired dermoid cysts originate from trauma, operator-induced, or iatrogenic implantation of the epithelial cells into surrounding tissues. They are commonly found in the head and neck region, with almost seven percent of dermoid cysts most often located on the floor of the mouth.
Acquired dermoid cysts may develop in any age group, but the highest incidence rates can be seen in patients between 15 and 35 years and have no gender prevalence. Dermoid cysts are distinct from epidermoid cysts, which lack these skin-related structures, and teratoid cysts, which contain tissues from various germinal layers and skin elements.
What Are the Clinical Features and Manifestations of Dermoid Cysts?
Dermoid cysts are asymptomatic during the onset and only become symptomatic when they grow in size. The most common clinical symptom of a dermoid cyst is when it suddenly appears on the floor of the mouth or the cervicofacial regions. These large-sized cysts cause interference while eating, speaking, and swallowing.
The clinical manifestations of dermoid cysts are as follows -
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They are benign and relatively slow-growing cysts that may remain initially asymptomatic.
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Patients usually observe this cyst only when it gains size and causes complications of acute or sudden onset inflammation in the cervical or orofacial regions.
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Difficulty in swallowing or dysphagia, dystonia, and airway obstruction (if they become large enough to affect the airway) are exacerbated effects of large untreated dermoid cysts.
In some patients, the large dermoid cysts can cause the displacement of the tongue or may rupture, leading to an acute inflammatory infection. These cysts are mostly benign unless left untreated and can turn into a chronic condition leading to malignant transformation with less than five percent transformation rates.
How to Distinguish Dermoid Cysts From Teratomas?
The differential diagnosis of dermoid cysts includes:
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Head and neck teratomas.
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Oral necrotic or slow-growing neoplasms of the oral cavity.
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Oral hematomas.
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Lymphatic malformations.
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Suppurative nodes of the orofacial region.
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Orofacial or space abscesses.
The dermoid cysts can be differentiated from conventional teratomas by histopathologic study or microscopic examinations. Teratomas have a broad spectrum of cysts commonly originating in the cervicofacial region. Various teratomas resemble dermoid cysts, including false teratomas, epidermoid cysts, and teratoid cysts, which are difficult to differentiate. The epidermoid cysts show fibrous walls lined with squamous epithelium that appear flattened, and dermoid cysts have fibrous walls containing one or more secondary structures associated with skin-like hair follicles and sebaceous glandular structures.
How to Diagnose Dermoid Cysts?
Various diagnostic and imaging modalities for identifying dermoid cysts are -
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Ultrasound Imaging: This is the diagnostic modality of choice for finding or detecting oral dermoid lesions. On ultrasound, dermoids appear well-circumscribed and have an unilocular cystic appearance. The cysts may contain three kinds of nodules - anechoic, hypoechoic, or multiple echogenic nodules representative of epithelial debris or appendages of skin.
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Computed Tomography (CT) Scan: This demonstrates the dermoid cyst having or being seen as a thin-walled cyst or unilocular mass. These are filled with homogeneous material with secondary multiple fat nodules, giving a hypoattenuating look. This appearance of a dermoid cyst on a CT scan is also called a ‘sack of marbles,’ which is a characteristic diagnosis for this condition.
Similarly, in many patients, the CT scans may also show specific areas of hypodensity with fat attenuation regions interspersed within, giving an accurate diagnosis through this imaging modality. Through Magnetic resonance imaging (MRI), the characteristics of dermoid cysts are variable. On the T2-weighted imaging modality, the dermoid cysts exhibit hyperintense signals compared to T1-weighted imaging, which accounts for variable signals depending on fat content.
What Is the Treatment of Oral Dermoid Cysts?
Imaging methods such as CT (computed tomography) or MRI (magnetic resonance imaging) scans are the most effective way to show the inside of dermoid cysts and provide a clear view of the cyst and surrounding anatomy. This helps guide surgeons in planning the best approach for treatment. The mylohyoid muscle is a crucial reference point separating different mouth and neck spaces. Surgeons use it to decide whether an approach from inside the mouth (intraoral) or neck (cervical) is more suitable for the surgery. Surgical removal with complete enucleation surgery is the primary treatment strategy for eliminating dermoid cysts.
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Treatment for small cysts above the geniohyoid muscle is possible through intraoral approaches by the oral and maxillofacial surgeon.
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Cysts that occur below the geniohyoid muscle region require extraoral surgical approaches. The surgeon will consider either an intraoral or extraoral approach based on the location of the mylohyoid muscle (that separates the sublingual space from submental and submandibular spaces).
However, the extraoral approach is highly preferred in the case of large cysts occurring in sublingual spaces. Following the surgical resection of dermoid cysts, the prognosis is excellent, with nil or minimal postoperative complications.
Conclusion:
To conclude, oral dermoid cysts have the nature of developing and progressing slowly over a while with acute manifestation and oral discomfort. Therefore, timely attention by the healthcare provider or the oral surgeon will aid in a good prognosis. Along with that, in some cases, the early management of dermoid cysts helps minimize the risk of malignant transformation and the recurrence rates of the cyst after resection.
