Odontogenic keratocyst

Findings

Multiple CT axial views of the mandible show a well corticated expansile cystic lesion with somewhat scalloped borders containing a comminuted pathologic fracture.
Figure 1: Comminuted pathologic fracture of an expansile lesion with well defined margins in the left mandible.
Figure 2: Soft tissue density likely secondary to protein/blood products.


Diagnosis: Odontogenic keratocyst


Odontogenic keratocysts also known as primordial cysts arises from remnants of dental lamina and make up 10% of jaw cysts. They occur more commonly in the 2nd to 4th decades and have a 2:1 M:F predilection.

75% are located in the posterior mandible around the 3rd molar. The most common maxillary location is the canine region. 50% are lucent, unilocular with well-defined sclerotic margins. Many cysts are expansile and multilocular.

The pathology demonstrates remnants of dental lamina. They are comprised of a fibrous wall lined by squamous epithelium with a low protein content. The cysts could have a low attenuation on CT likely due to low protein content or a high attenuation from hemorrhage. Theses cysts make up 10% of jaw cysts and are associated with Noonan and Marfan syndrome. A minority of odontogenic keratocysts are multiple and 50% of these cases will have associated basal cell nevus.

Approximately 50% of patients are symptomatic with jaw swelling being the most common symptom, seen in up to 85% of symptomatic patient. Other signs and symptoms include sinus tract with drainage seen in 15%, pain, paresthesia and trismus.

The natural history of odontogenic keratocysts are rapid growth with high recurrence rate. Treatment is with enucleation and aggressive curettage. Due to high recurrence rate follow up studies are recommended.