Ameloblastomas are locally invasive and destructive benign odontogenic tumors that arise from rests of the dental lamina. Their recurrence rate is high [3, 4] even for patients that undergo surgical excision of the tumor even in excised tumors with free safety margin. The immunohistochemistry can describe the biological differences of these tumor types . This study was carried out to elucidate the relationship between the expression of EGFR, CD10 and Ki-67 labelled index and ameloblastoma recurrence using clinical and pathological data.
Normal EGFR signaling plays an essential role in organ development, repair and in the regulation of cell survival. Aberrant signaling can be the result of EGFR overexpression by EGFR gene amplification or mutations with ligand-independent tyrosine kinase activity which could result in uncontrolled cell division; a predisposition for cancer [25, 26]. EGFR upregulation appeared to be selectively expressed in a number of tumors as glioblastomas and lung cancer .
In the current study, all ameloblastomas exhibited EGFR immunoexpression with no identified relation to recurrence. Previous studies in the literature evaluated EGFR expression in ameloblastomas [19, 28, 29], and their results were divergent. Shrestha et al.  claimed that of the 23 cases of examined solid ameloblastomas, none demonstrated EGFR expression. However, Li et al.  reported that EGFR was detected in all six of their cases of ameloblastoma. Ueno et al.,  examined 39 cases of solid ameloblastoma and EGFR expression was found in 30 (88%). Vered et al.,  reported that all specimens were EGFR-positive using membranous, or both membranous and cytoplasmic staining as positivity criteria. Our results were mainly consistent with the latter finding. The differences between previous reports may be explained by the different positivity criteria adopted, such as only membrane labeling , or membrane and cytoplasmic labeling associated with labeling intensity [19, 29].
CD10 is associated with differentiation and growth of neoplastic cells, and its expression is found to be increased with the increase of tumor dysplasia. Ogawa et al.,  found that there was no expression of CD10 in the stromal cells of normal colorectal tissue, while the percentage of CD10+ stromal cells were increasing adjacent to tumor cells with increasing dysplasia in adenomas and maximally found in stroma adjacent to invasive carcinoma . Iwaya et al.,  found that there was no staining in the stromal cells of noninvasive ductal carcinoma or normal breast tissue, while the frequency of positive stromal staining increased in cases with axillary lymph node metastases . In the study of Makretzov et al.,  stromal CD10 positivity, seen at the invasive front, was associated with higher tumor grade, and decreased survival in breast carcinoma, suggesting tumor-stromal interactions. In a study of CD10 in oral squamous cell carcinoma, it was found that CD10 positivity in stromal cells was an indicator of worse prognosis; a significant correlation was found with lymph node metastases, local recurrences, and histologic grade .
Ameloblastoma is a tumor that shows heterogeneous expression of CD10 . Most recurrent tumors strongly express CD10 and could be a marker for aggressive behavior. Our data demonstrated that patients with tumors strongly express CD10 in the peritumoral stromal cells were more prone to local recurrence after resection with uninvolved cut margins. This is similar to the results in studies done by Lezzi et al.,  and Masloub et al., . It is possible then that the function of CD10 is employed primarily in invasion of extracellular matrix. The presence of CD10+ stromal cells may signify the aggressiveness of tumor. Similarly, Bilalovic et al.,  reported metastatic behavior of melanoma cases with peritumoral CD10 positive stain.
Assessment of cell proliferation in many types of tumors is important together with histologically based tumor classification and has potential relevance as an indicator of tumor behavior, treatment response and relapse . The results of this study showed that cellular proliferative activity as assessed by Ki67 labeling indices varied within recurrent and non-recurrent cases of ameloblastoma. There was a significant relation between labeling index of nuclear proliferation marker ki67 and recurrence of ameloblastoma. This is in concordance with Hirayama et al.,  who found a high proliferative activity in recurrent ameloblastoma. In this study, the assessment of the cellular proliferation marker was shown to be reliable and reproducible.
All the above-mentioned immunohistochemical data indicated that the immunoexpression of CD10 and Ki67 labeling index may be good predictor for recurrence in ameloblastoma.