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Odontogenic Keratocyst

What is Odontogenic keratocyst?

The odontogenic keratocyst can be defined as a cystic benign tumor, being localized at the level of the mandible or the maxilla. Also known as the keratocystic odontic tumor, it is believed to be stemming from the dental lamina. This condition is often encountered in young patients, who are in their 2nd or 3rd decade of life. It is found in association with the following medical conditions: Noonan syndrome, Marfan syndrome or basal cell nevus syndrome (most common association, this condition is also known as the Gorlin-Goltz syndrome). The odontogenic keratocyst was described for the first time in 1876 and it was later (1956) characterized in detail, by Philipsen. Today, it is known that 3-11% of all the diagnosed cysts at the level of the jaw are actually odontogenic keratocysts.


More than one cyst is present in the majority of the patients, the most common area being the body or the ramus of the mandible (70% of all the cases). As it was already mentioned, these cysts can be found at the level of the maxilla as well. Men are more commonly diagnosed with this condition than women. This condition is as rare as it is aggressive. More recently, the World Health Organization has re-classified this condition from cyst to tumor – this change is related to the aggressive nature of this lesion and it also forces doctors to manage the condition in a manner that is just as aggressive.

Pathophysiology

Histopathological studies have demonstrated that the odontogenic keratocysts originate from epithelial cell rests. These rests are actually represented by the stratified squamous keratinizing epithelium and they are found along the dental lamina. They are also found along the periodontal margin of the mandible alveolus. One of the areas in which is more commonly located is the posterior mandible, its aggressiveness being related to it being a developmental and cystic neoplasm. In very rare cases, the odontogenic keratocyst has been found at the level of the temporomandibular joint. Despite it being presented as an intraosseous lesion, there are patients who present peripheral manifestations. The buccal gingival soft tissue can be affected by the presence of the odontogenic keratocyst, especially at the level of the canine area of the mandible.

Symptoms

In the majority of the cases, the odontogenic cyst is asymptomatic and it is found incidentally, upon performing a dental X-ray for other problems. Some patients might present inflammation in the respective area (most common complaint).

Causes

At the moment, the exact cause that leads to the appearance of the odontogenic keratocyst is not known. However, recent studies have started to incriminate genetics among the potential causes. It seems that the odontogenic keratocyst (sporadic and non-sporadic) is often found in association with a mutation that occurs at the level of the gene PTCH.

Pictures of Odontogenic Keratocyst

odontogenic keratocyst
Picture 1 : Radiographic presentation of Odontogenic Keratocyst

Diagnosis

These are the most common methods used for the diagnosis of the odontogenic keratocyst:

Imaging studies

  • X-ray
    • Specific aspect – lucent lesion with smooth and corticated borders
    • If located at the level of the mandible, the growth typically occurs along the bone length
    • When found in the maxilla, the cysts might develop as far as the maxillary sinus; may also involve the floor of the nose
    • Often associated with impacted teeth (all signs point to the dentigerous cyst, even though this is not the situation)
    • Septated appearance (occasionally) – might make the differential diagnosis with ameloblastoma difficult
    • Multiple keratocysts present – suggestive of the association with the Gorlin-Goltz syndrome
  • MRI
    • Recommended for the confirmation of the diagnosis.

According to the changes identified through imaging investigations, the differential diagnosis can be made with the following conditions: dentigerous cyst, ameloblastoma and calcifying odontogenic cyst (Gorlin cyst).

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The final diagnosis is made upon the histologic analysis, preceded by the excision of the respective cyst. The histologic analysis is performed with the help of the microscope – this analysis will be used for the confirmation of the diagnosis. The pathologist will make the difference between the actual odontogenic keratocyst and the keratinized squamous epithelium. While these two bear somewhat of a resemblance, the microscope analysis will reveal that the keratocysts do not present rete ridges and they are separated from the basement membrane.

Treatment

It is important to understand that these odontogenic keratocysts can be quite aggressive, destroying the local tissues. For these health concerns, these are the most common treatment approaches: enucleation, excision and/or curettage. The wide surgical excision is often performed in patients who have multiple keratocysts present.

A more recent technique – marsupialization – has been used for the treatment of the odontogenic keratocyst. This technique involves the opening of the cavity in which the keratocyst is located, followed by the creation of a marsupial-like pouch (hence the name of the procedure). The cavity will remain in contact with the outside for a longer period of time, such as three months.

The curettage, as you are probably aware, refers to the simple excision of the keratocyst, followed by the scraping out of the respective cavity. Sometimes, after a procedure so aggressive as the curettage or the enucleation, the peripheral ostectomy is necessary. Other solutions for treatment include: simple excision (no scraping out), Carnoy’s solution (often used at the same time with the excision of the keratocyst) and cryotherapy (performed at once with enucleation). Recent studies have demonstrated that the resection or the enucleation, used in conjunction with Carnoy’s solution or the peripheral ostectomy, results in a higher recurrence rate than the enucleation used alone or the marsupialization procedure.

At the moment, the most effective intervention is represented by the enucleation procedure, used in conjunction with Carnoy’s solution or the marsupialization, followed by the later cystectomy. Studies are being performed to investigate the efficiency of molecular-based treatments, which may eliminate the need for medical treatments that are highly aggressive (such as the above-mentioned surgical interventions).

Prognosis

Unfortunately, the risk of recurrence is quite high (between 30% and 60%). It is possible that, in rare cases, the odontogenic keratocyst progresses to squamous cell carcinoma (malignant transformation).

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