Analysis of argyrophilic nucleolar organizer region score and epithelial dysplasia in common odontogenic cysts seen in a university teaching hospital

Aim: Carcinomatous transformation in odontogenic cysts (OC) lining may be more common than is generally appreciated. Thus, the aim of this study is to predict the potential for neoplastic transformation in the epithelial lining of OC using argyrophilic nucleolar organizer region (AgNOR) scores and degree of epithelial dysplasia. Subjects and Methods: A retrospective clinicopathological study was undertaken on OC histologically diagnosed over a 40-year period in a university teaching hospital in Southwestern Nigeria. Paraffin blocks of selected cases were retrieved and sectioned for hematoxylin and eosin and AgNOR stain. Evaluation of epithelial dysplasia was done using the WHO 2005 protocol. Estimation of atypical features and AgNOR scoring were done using modified and established protocols. Epi info and GraphPad InStat software packages were employed to manage the ensuing data. Results: The commonly observed OC was odontogenic keratocyst (OKC), which accounted for 44.5%, radicular cyst (RC) (24.2%), calcifying odontogenic cyst (COC) (12.7%), and dentigerous cyst (DC) (11.5%). Nuclear pleomorphism was the most common atypical feature and was present in 50% each of DC and COC, 42% of OKC, and 36% of RC. Drop-shaped rete pegs were rarely observed. A significant association was observed between the presence of moderate dysplasia and histologic type of OC (P = 0.022). Mean AgNOR scores per 100 cells was OKC (137.38 ± 35.82), RC (132.04 ± 34.22), COC and DC (119.00 ± 10.93) and (96.91 ± 38.88) respectively. This was not statistically significant (P = 0.218). Conclusions: As moderate epithelial dysplasia was more significantly associated with OKC than other cysts, it is concluded that the potential for malignant transformation is higher in OKC than other histologically categorized types of cysts.