Objective To investigate the potential role of Spa-1 in the development and metastasis of EMPD.Methods Tissue specimens were resected from 17 patients with primary EMPD,12 patients with invasive EMPD and 9 normal human controls.Immunohistochemistry was performed to measure the expression of spa-1 and Ki-67.Results Positive staining was observed for Spa-1 in cytoplasm,and for Ki-67 in cell nuclei.Spa-1 and Ki-67 were weakly expressed in the basal layer of normal skin.The expression of Spa-1 and Ki-67 in EMPD tissue were statistically higher than those in the normal control tissue (both P<0.01).Increased expression of Spa-1 was noted in invasive EMPD tissue compared with in situ EMPD tissue.The expression of Spa-1 was positively correlated with that of Ki-67 in the tissue of EMPD.Conclusion Spa-1 may play a certain role in the initiation and progression of EMPD.