Odontogenic keratocyst typically presents in young adults, particularly males in their second to third decade of life, with a painless, slowly enlarging multilocular cyst at the posterior mandible which has a thin, keratinised epithelial lining.
Description
An odontogenic keratocyst (OKC) is a benign but aggressive developmental cyst, originating from the dental lamina1. It is known for its unique histopathological features and a high recurrence rate. OKCs are significant for their association with the nevoid basal cell carcinoma syndrome (Gorlin syndrome).
Pathogenesis
The pathogenesis involves the activation of the PTCH gene, leading to abnormal proliferation of the odontogenic epithelium. The cysts are derived from cell rests of the dental lamina, contributing to their unique location and behavior.
Subtypes
- Sporadic Odontogenic Keratocyst: The most common type, occurring without association with any syndrome.
- Syndromic Odontogenic Keratocyst: Associated with Gorlin syndrome, presenting multiple keratocysts.
Epidemiology, Risk Factors & Associations
- Predominantly affects young adults (20s and 30s).
- Higher incidence in males.
- Multiple OKCs associated with Gorlin syndrome.
Clinical Features
- Asymptomatic in early stages, detected incidentally on imaging.
- Jaw swelling and pain in larger cysts.
- Potential for disfigurement and tooth displacement.
Complications
- High recurrence rate post-treatment.
- Rare malignant transformation to squamous cell carcinoma.
- Potential for significant bone destruction and tooth displacement.
- If large enough, may resorb the roots of adjacent teeth.
Pathological Features
Histopathology
- Macroscopic: Cystic lesion filled with keratinous material.
- Microscopic: Characterised by a thin, parakeratinised epithelium, usually 5-8 cell layers thick, with a corrugated surface.
Serology
- Not applicable.
Biochemistry
- Not relevant.
Radiological Features
General Features
- Typically a solitary, well-defined, unilocular, radiolucent, expansile lesion
- Predominantly located in the posterior mandible (body or ramus) or maxilla
- Can expand cortical bone and erode the cortex
- If associated with the crown of an unerupted/impacted tooth, they can mimic a dentigerous cyst
- If associated with the roots of a non-vital tooth, they can mimic a radicular cyst
XR
- Panoramic radiographs show well-demarcated lesions.
CT
- Non-contrast: Expansile, cystic lesion with scalloped, well-corticated borders. Density varies with viscosity. Cortical breach suggests possible soft tissue involvement.
MRI
- T1: High signal due to cholesterol and keratin contents
- T2: Heterogenous signal
- DWI/ADC: Diffusion restricts due to prescence keratin
- T1 Gad+: Peripheral enhancement.
NM
- PET FDG: Not typically used.
Grading and Staging
No standard grading or staging system for odontogenic keratocysts.
Diagnosis
Based on clinical, radiographic, and histopathological findings. Imaging is crucial for initial detection and surgical planning.
Differential Diagnosis
- Ameloblastoma: Radiographically similar but histologically distinct.
- Dentigerous cyst: Associated with the crown of an unerupted tooth.
- Radicular cyst: Associated with the apex of a non-vital tooth.
Management
- Surgical enucleation and curettage with close follow-up due to high recurrence.
- Marsupialisation for large cysts.
- Resection in cases of extensive involvement or recurrent lesions.
- Regular radiographic follow-up post-treatment to monitor for recurrence.
References