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Odontogenic Keratocyst/Keratocystic Odontogenic Tumor

The odontogenic keratocyst is a developmental odontogenic cyst with a tendency to recur, characterised by a histological appearance of parakeratinized lining epithelium with palisaded ameloblast-like basal cells.

Are significant for three reasons:

1. Greater growth potential than most other odontogenic cysts

2. Higher recurrence rate

3. Possible association with the nevoid basal cell carcinoma syndrome

Although there are wide variations in the reported frequency of OKCs compared with that of other types of odontogenic cysts, most studies indicate that OKCs make up 3% to 11% of all odontogenic cysts.

 

Clinical features

Peak incidence is between ages 20 and 30 years, but the age range is very broad.

The mandible is usually affected. At least 50% of odontogenic keratocysts form in the posterior body and lower ramus.

Odontogenic keratocysts, like other jaw cysts, are symptomless until the bone is expanded or they become infected, both rare features in this cyst type.

Lesions found in children are often reflective of multiple cysts as a component of NBCCS.

 Approximately 5% of patients with OKCs/KCOTs have multiple cysts and another 5% have NBCCS.

Radiography features

Odontogenic keratocysts produce well-defined radiolucent areas, with a more or less rounded or scalloped margin.

 Some are unilocular, but the majority are multilocular. 

The margin is sharply demarcated and corticated radiographically.

The characteristic growth pattern is evident radiologically and is almost diagnostic. There is extensive spread forward and backward along the medullary cavity with minimal expansion until the whole of the medulla is replaced.

There is minimal displacement and no resorption of teeth or the inferior dental canal.

 In a minority of cases, the cyst may arise at the site of a tooth that has failed to develop (Primordial cyst)

The lack of expansion results in many odontogenic keratocysts being large at time of discovery.

Odontogenic Keratocyst: Key  Features

Aggressive; recurrence risk; association with nevoid basal cell carcinoma syndrome

Solitary cysts: common (5%-15% of odontogenic cysts); recurrence rate 10% to 30%

Multiple cysts: 5% of OKC patients; recurrence greater than with solitary cysts

Syndrome-associated, multiple cysts: 5% of OKC patients; recurrence greater than with multiple cyst

OKCs demonstrate a well-defined radiolucent area with smooth and often corticated margins. Large lesions, particularly in the posterior body and ramus of the mandible, may appear multilocular

 Preoperative radiograph showing an extensive radiolucent lesion spanning across the whole length of the mandible from one condyle to the other

Radiograph at 2-year follow-up showing reduction in the radiolucency of the lesion from the periphery, except for the region between lower right lateral incisor and canine

Treatment protocol undertaken in the above case

Marsupialization.

 Immunohistochemical analysis revealed reduced expression of Ki-67 and B cell lymphoma 2 (bcl-2) markers after marsupialization from 2 separate sites.

Due to incomplete resolution in the lower right anterior region, an aggressive approach by  Surgical curettage along the  associated teeth and cortical plate followed by application of Carnoy's solution.

ing across the whole length of the mandible from one condyle to the other.

 Odontogenic keratocyst. Part of a panoramic tomogram showing typical appearances. The cyst is multilocular and has extended a considerable distance along the medullary cavity without appreciable expansion or displacement of the teeth.

 Odontogenic keratocyst. Huge lesion extending from coronoid to the opposite molar region with minimal tooth displacement or expansion of bone.

• Figure 10-28​Multiloculated odontogenic keratocyst of the mandibular ramus.

An extensive keratocystic odontogenic tumor as a multilocular radiolucent lesion in the left mandibular ramus in close approximation to the impacted third molar.

Graphical network of the top 20 diseases related to Keratocystic Odontogenic Tumor

Differential diagnosis

When cysts are associated with teeth, several entities might be considered, such as dentigerous cyst, ameloblastoma, odontogenic myxoma, adenomatoid odontogenic tumor, and ameloblastic fibroma. Radiolucent, nonodontogenic tumors, such as central giant cell granuloma, traumatic bone cyst, and aneurysmal bone cyst, might be included in a differential diagnosis of this entity in young patients.

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