title: Correlation between ploidy status using flow cytometry and nucleolar organizer regions in benign and malignant epithelial odontogenic tumors.
abstract: OBJECTIVE
  Differentiation between the aggressive benign odontogenic tumors and their malignant counterparts is controversial and difficult. While flow cytometry (FCM) allowed DNA analysis in neoplasia, argyrophilic organizer regions (AgNORs) number and/or size in a nucleus are correlated with the ribosomal gene activity and therefore with cellular proliferation. The aim of this research was to study the diagnostic accuracy of FCM and AgNORs staining in differentiating between benign and malignant epithelial odontogenic tumors and to correlate between these two interventions.
  
  
  METHODS
  Sixteen benign cases [8 cases of ameloblastoma (AB) and 8 cases of keratocystic odontogenic tumor (KCOT)] and 13 malignant epithelial odontogenic tumors [8 cases of ameloblastic carcinoma (ABC) and 5 cases of clear cell odontogenic carcinoma(CCOC)] were included in the current study. For FCM analysis, a single cell suspension from Formalin fixed paraffin-embedded (FFPE) tumors was prepared according to a modified method described by Hedley (1989) and AgNORs staining were performed in accordance to the Ploton protocol (1986). Analysis of AgNORs was performed using both quantitative and qualitative methods.
  
  
  RESULTS
  The work revealed that all the examined tumors were diploid, except for 40% of CCOC cases. The S-phase fraction (SPF) value, AgNORs count and AgNORs area/cell showed statistically significant difference on comparing benign and malignant groups. A weak positive correlation was observed between SPF and AgNORs count.
  
  
  CONCLUSIONS
  The SPF value was considered to be more sensitive and specific in differentiation between aggressive benign and malignant epithelial odontogenic tumors in comparison to AgNORs counting.
authors.affiliation: Faculty of Oral and Dental Medicine, Cairo University, 11222, Egypt. Electronic address: sarah.badawy@dentistry.cu.edu.eg.
authors.forename: Sarah Ahmed
authors.initials: SA
authors.lastname: Mohamed Mahmoud
authors.affiliation: Faculty of Oral and Dental Medicine, Cairo University, 11222, Egypt. Electronic address: daliael.rouby@dentistry.cu.edu.eg.
authors.forename: Dalia Hussein
authors.initials: DH
authors.lastname: El-Rouby
authors.affiliation: Faculty of Oral and Dental Medicine, Cairo University, 11222, Egypt. Electronic address: safa.fathy@dentistry.cu.edu.eg.
authors.forename: Safa Fathy Abd
authors.initials: SF
authors.lastname: El-Ghani
authors.affiliation: National Cancer Institute, Cairo University, Egypt.
authors.forename: Omnia Mohamed
authors.initials: OM
authors.lastname: Badawy
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000473:pathology*; D000564:Ameloblastoma / Q000473:pathology*; D005434:Flow Cytometry; D006801:Humans; D009697:Nucleolus Organizer Region / Q000473:pathology*; D009808:Odontogenic Tumors / Q000473:pathology*; D011003:Ploidies; D012680:Sensitivity and Specificity; D013194:Staining and Labeling
keywords: AgNORs; Ameloblastic carcinoma; Ameloblastoma; Clear cell odontogenic carcinoma; Flow cytometry; Keratocystic odontogenic tumor