Odontogenic cysts are common lesions in the oral and maxillofacial region, originating from the tissues involved in tooth development. They are categorized into several types based on their histological and clinical characteristics, with three prominent types being odontogenic keratocysts (OKCs), dentigerous cysts (DCs), and radicular cysts (RCs). Differentiating these cysts is critical for accurate diagnosis and effective treatment planning, as they exhibit distinct behaviors and recurrence rates.

Odontogenic keratocysts (OKCs) are known for their aggressive nature and high recurrence rates. They typically occur in the posterior mandible and are characterized by a potential association with genetic syndromes like nevoid basal cell carcinoma syndrome.

Dentigerous cysts (DCs) are developmental cysts that surround the crown of an unerupted tooth. They are more common and generally considered less aggressive compared to OKCs. DCs have a lower recurrence rate after surgical removal.

Radicular cysts (RCs) are inflammatory cysts that arise at the apex of a non-vital tooth. They are the most common type of odontogenic cyst and typically show less aggressive behavior.

Distinguishing between these cysts can be challenging due to overlapping clinical and radiographic features. Histological examination, including immunohistochemical staining for cytokeratins, is often used to differentiate these cysts. Cytokeratin 19 (CK19) is a marker associated with epithelial cells and has been studied for its potential to aid in the differential diagnosis of odontogenic cysts.

Previous studies have shown varying CK19 expression in these cysts, prompting Maha Thayir Hadi and Layla Sabri Yas to investigate CK19 expression patterns in OKCs, DCs, and RCs to assess its utility in differentiating these lesions. Understanding CK19 expression could enhance diagnostic accuracy for these cystic lesions.

Materials and Methods

The study analyzed 45 formalin-fixed, paraffin-embedded tissue blocks (15 each of OKC, DC, and RC) obtained from the University of Baghdad archives. Immunohistochemical analysis was performed using CK19 antibodies. Tissue sections were divided into surface, spinous, and basal layers to evaluate CK19 expression. Staining patterns were classified as negative (less than 10% positive cells at each layer), +1 (between 10% and 50% positive cells at each layer), or +2 (more than 50% positive cells at each layer) based on the percentage of positive cells. Statistical analysis using the Chi-square test assessed differences in CK19 expression among the cyst types.

Results

The study revealed that OKCs exhibited significantly lower CK19 expression in the basal layer compared to DCs and RCs, with 80% of OKC samples showing negative CK19 in this layer. In contrast, DCs and RCs showed higher positivity in the basal layer, with 60% and 53.3% respectively. No significant difference in CK19 expression was found between groups in the surface and spinous layers. Statistical significance was observed for CK19 expression in the basal layer (P = 0.034) but not in the surface and spinous layers (P = 0.103). These findings align with previous research suggesting that CK19 expression can aid in distinguishing between these cyst types.

Conclusion

The immunohistochemical expression of CK19 varies among OKCs, DCs, and RCs, correlating with their epithelial differentiation. CK19 serves as a diagnostic biomarker to distinguish these cystic lesions. The study emphasizes that well-differentiated cysts (DCs and RCs) have higher CK19 expression, while OKCs show less positivity.

Given the aggressive nature and recurrence of OKCs, their lower CK19 expression levels in the basal layer suggest a potential role of these basal cells in the lesion's behavior. This study proposes that CK19, along with other epithelial markers, could enhance diagnostic accuracy for odontogenic lesions.

• Cytokeratin 19 Polyclonal Antibody
• Cytokeratin 19 Monoclonal Antibody
• Cytokeratin 19 ELISA Kit
• Cytokeratin 19 Protein