Open Journal of Stomatology, 2013, 3, 520-526 OJST http://dx.doi.org/10.4236/ojst.2013.39086 Published Online December 2013 (http://www.scirp.org/journal/ojst/ ) Ki-67 immunohistochemical expression in mandibular ameloblastoma: A prognostic indicator for local recurrence Ayman Hegab 1*# , Mohmmad Shuman 2† , Mohammed Abd El-Akher 1# , Delaram Arwlan 3 1 Oral and Maxillofacial Surgery, Faculty of Dental Medicine, Al-Azhar University, Cairo, Egypt 2 Oral and Maxillofacial Surgery, Faculty of Dental Medicine, Al-Azhar University, Assuit, Egypt 3 Medcal City Teaching Hospital, Teaching Laboratory, Baghdad, Iraq Email: * hegab@mail.com Received 12 September 2013; revised 12 November 2013; accepted 29 November 2013 Copyright © 2013 Ayman Hegab et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Objective: This study used Ki-67 to evaluate the pro- liferative activity of ameloblastoma in an attempt to provide a scientific basis for any differences in the biologic behaviour that exists between the different types of ameloblastoma and correlate the results with the recurrence rate. Study design: We assessed Ki-67 expression by immunohistochemistry in 32 cases of mandibular ameloblastoma. Formalin-fixed, paraffin- embedded blocks were sectioned and used for Hae- matoxylin & Eosin (H&E) staining. H&E slides were used to re-evaluate the histological types of the amelo- blastoma. Immunohistochemical analysis for Ki-67 with a labelled streptavidin-biotin-peroxidase com- plex technique was performed on tumour sections using Monoclonal Mouse Anti-Human Ki-67 Antigen (clones MIB1, code M7240, Dako Corporation). Lym- ph nodes (lymphoma) were used as positive control for Ki-67. Results: The specimens comprised 18 cases of Follicular ameloblastoma, 7 cases of Cystic amelo- blastoma, 4 cases of plexiform ameloblastoma, and 3 cases of Acanthotic ameloblastoma. The results show- ed that cellular proliferative activity varied within the ameloblastoma types. There was no statistically sig- nificant difference in the Ki-67 Acanthotic, cystic and follicular types of ameloblastoma, while plexiform type showed statistically significantly higher levels than the other 3 types. The mean Ki-67 labelling in- dex of plexiform ameloblastoma ranged from 13 to 30 with a mean of 19.75. The mean values of Ki-67 were statistically significantly higher in recurrent than non-recurrent cases. Conclusion: The significant ex- pression of Ki-67 could provide useful prognostic markers for proliferative activity and good prognostic indicators for recurrence rate of mandibular amelo- blastoma. Keywords: Mandibular Ameloblastoma; Recurrence; Immunohistochemistry; Ki-67 1. INTRODUCTION Ameloblastoma is a Benign Tumour of Odontogenic epithelium with mature fibrous stroma without odonto- genic ectomesenchyme. In the updated World Health Or- ganization (WHO) classification, it was classified into solid/multicystic type, extra-osseous/peripheral type, des- moplastic type and unicystic type [1]. Histologically, there are two main patterns, follicular and plexiform, in which various cellular changes such as squamous metaplasia and granular transformation are commonly seen, and when these are extensive, the terms acanthomatous type and granular cell type are applied, respectively. Cyst formation within the epithelial islands of the follicular type is common. Other rare histological variants, including basal cell ameloblastoma, desmoplas- tic ameloblastoma and kerato ameloblastoma, have also been described. Despite numerous studies, correlation between these histological patterns and tumour behav- iour has not been consistently established [2]. The me- chanisms of oncogenesis, cytodifferentiation and tumour progression of ameloblastoma are still largely unknown [3,4]. * Corresponding author. # Associate Professors of Oral and Maxillofacial Surgery, Faculty of Dental Medicine, Al-Azhar University, Cairo, Egypt. † Lecturer of Oral and Maxillofacial Surgery, Faculty of Dental Medi- cine, Al-Azhar University, Assuit, Egypt. Determination of epithelial proliferative activity is apotentially useful means of investigating differences in- biologic behaviour between tumours [5-7]. Assessment OPEN ACCESS