Abstract: Objective: To detect the expression of E-cadherin and β-catenin in the pathological tissues of patients with extramammary Paget's disease (EMPD), and analyze the clinical significance and relationship of E-cadherin and β-catenin in the pathogenesis and metastasis of EMPD. Methods: The EMPD tissue specimens and preputial tissue as control were collected, and the expressions of E-cadherin and β-catenin were detected by immunohistochemistry, the result was determined by the product of staining intensity and staining percentage score. Results: Thirty-three EMPD tissue and 25 preputial tissue specimens were collected. Immunohistochemical results showed that the positive expression of E-cadherin and β-catenin was mainly located on the cell membrane. The strong positivity rates of E-cadherin and β-catenin in EMPD patients were 0% and 3.0%, the positivity rates were 36.4% and 54.5%, the weak positivity rates were 51.5% and 24.2%, and the negativity rates were 12.1% and 18.2%, respectively. The expression of E-cadherin and β-catenin in normal tissues were all strongly positive. There were significant differences of E-cadherin andβ-catenin expression between EMPD lesions and control tissues (Ps<0.05).  The expression level of E-cadherin was not significantly correlated with age, sex and lymph node metastasis in patients with EMPD (P>0.05), and significantly correlated with the occurrence of dermal infiltration (P<0.05). E-cadherin was positively correlated with β-catenin expression (r=0.490，P＜0.01）. Conclusion: The expression of E-cadherin and β-catenin in EMPD is synergistic. The downregulation of E-cadherin expression may be associated with invasion of EMPD tumors, but may not be associated with EMPD metastasis.

Key words: extramammary Paget's disease, E-cadherin, β-catenin, immunohistochemistry