Odontogenic Keratocyst

• This lesion can occur at any age, but is exceedingly rare under the age of 10.
• The peak incidence is in the third and fourth decades of life, with a smaller peak in the elderly.
• There is a slight predilection for males.
• The mandible is invariably affected more frequently than the maxilla.
• In the mandible, it is followed by the first and second molar areas, the ramus third molar areas, and then the anterior mandible.
• In the maxilla, the most common site is the third molar area followed by the cuspid region.
• Lesions found in children are often reflective of multiple OKC as a component of the NBCCS, but at other times, these multiple cysts are independent of the syndrome.
• About 50% of patients are asymptomatic prior to seeking treatment.
• Common features are pain, soft tissue swelling and expansion of bone, drainage, and various neurologic manifestations such as paresthesia of the lip or teeth.
• Maxillary lesions tend to be secondarily infected more frequently than mandibular ones, due to its vicinity to the maxillary sinus.
• The aspirate from this lesion mostly contains a cheesy material suggestive of keratin.
• Sometimes, the aspirate may also contain a straw-colored fluid.

Radiographic Features

• Radiographically, OKCs present as a unilocular radiolucency with a well-defined peripheral rim.
• Scalloping of the border is also a frequent finding, representing variations in the growth pattern of the cyst.
• Multilocular radiolucent OKC is also observed, generally representing a central cavity having satellite cysts.
• When it is multilocular and especially if located in the mandibular third molar area, it may be confused radiographically with an ameloblastoma.
• Occasionally, the lesion may mimic a dentigerous cyst if it contains the crown of an impacted tooth within its lumen.
• Sometimes lesions tend to grow in antero-posterior directions resulting in large lesions, but clinically present as small or no swelling with little cortical expansion.
• Multilocularity (20%) is often present and tends to be seen more frequently in larger lesions.
• Most lesions, however, are unilocular, with as many as 40% noted adjacent to the crown of an unerupted tooth (dentigerous cyst position).
• Approximately 30% of maxillary and 50% of mandibular lesions produce buccal expansion.
• Mandibular lingual enlargement is occasionally seen.
• Proximity to the roots of adjacent normal teeth sometimes causes resorption of these roots, although displacement is more common.
• Sometimes these cysts displace the neurovascular bundle.
• Some atypical manifestations of the keratocyst include an extrasseous form as a peripheral OKC that occurs in gums, cheek tissue, and deep lateral facial region.
• Cases of pigmented OKCs have been reported in young females with an average age of 18 years, where the pigmentation is due to the presence of melanocytes without atypical features within the squamous epithelium of the tumor.

Histologic Features

• The final diagnosis of any cystic cavity within the jaw bones is achieved by histopathological examination of the biopsied or resected surgical specimen.
• The wall of OKC is usually rather thin, unless there has been superimposed inflammation.

Epithelium lining

• A parakeratinized surface, which is typically corrugated, rippled, or wrinkled.
• A remarkable uniformity of thickness of the epithelium, usually ranging from five to eight cells.
• A prominent palisaded, polarized basal layer of cells often described as having a "picket fence" or "tombstone" appearance.