Abstract: OBJECTIVE: To investigate the expression of MUM1 protein in T_cell lymphoma and its relationship with tumor cell proliferation. METHODS: The expressions of MUM1 protein and ki_67 in 58 specimens of T_NHL were analyzed by immunohistochemistry, including 9 cases of precursor T lymphoblastic lymphoma/leukemia(T_LBL/L),12 cases of anaplastic large T cell lymphoma(ALCL) and 37 cases of peripheral T cell lymphoma(PTL). Two cases of reactive hyperplastic lymphadenitis were used as comparison. We also analysed the relationship between MUM1 protein in tumor and ki_67 proliferation index. RESULTS: MUM1 protein expression was positive in 1 of 9 T_LBL/L, 9 of 12 ALCL and 26 of 37 PTL by immunohistochemistry.The expression rate of MUM1 protein in T_LBL/L was significantly lower than that in ALCL and PTL(P<0.05). The expression rate of MUM1 protein was similar in ALCL and PTL(P>0.05). There was no significant difference in MUM1 positive group of ki_67 proliferation index(53.61±23.83)％ compared with MUM1 negative group (53.27±21.23)％(P>0.05). CONCLUSION: The expression of MUM1 in T cell lymphoma may be associated with cell activation but not directly related to the proliferation of tumor cells.

Key words: T_cell lymphoma, MUM1 protein, ki_67 cell proliferation index