Objective       To determine the expression levels of bone morphogenetic protein-2 (BMP-2) and X-linked inhibit apoptosis protein (XIAP) in cell-rich and matrix-rich pleomorphic adenoma in order to clarify the correlation of their expression with canceration and recurrence.       Methods        Clinical data of 92 cases of pleomorphic adenoma admitted in our department from January 2004 to January 2013 were collected and analyzed in this study. All the obtained tissue specimens were observed morphologically after HE staining

and then grouped as cell-rich group (A)

matrix-rich group (B) and other type group (C). Immunohistochemical staining was used to detect the expression of BMP-2 and XIAP in the 3 groups of specimens. Cell apoptosis was assessed by TUNEL assay. The recurrence and malignant cases were analyzed based on medical records

and the results were analyzed with the expression levels of BMP-2 and XIAP separately.       Results        The expression level of BMP-2 was highest in the group B

followed by the group C and group A in order. XIAP was expressed in highest level in the group A

and then weakened in the group B and group C

with significant differences between any 2 groups (P0.05). The expression of BMP-2 were significantly higher in the recurrence cases than in the non-recurrence cases (P0.05). The expression of XIAP were obviously stronger in the malignant cases than in the non-malignant cases (P0.05). TUNEL assay showed that group A had the lowest apoptotic index

which was significant lower than the other 2 groups (P0.05)

while no significant difference was found between the group B and group C.       Conclusion        Matrix-rich pleomorphic adenoma is more prone to recurrence than other types

while cell-rich one is more easy to be malignant transformation. The expression level of BMP-2 may be associated with recurrence

while that of XIAP with canceration.