Expression And Significance Of β5t, P63 And CD20 In Thymoma

Purpose:To study.the expression ofβ5t p63 and CD20 and their significiance in thymoma.Methods:The microscopic and immunohistochemical features were examined in 34 cases of thymoma, with review of relatedliteratures.Results:(1)There were 4 cases of TAT,9 cases of TABT,10cases of TB1T、 6 cases of TB2T,2 cases of TB3T,1 case of TB2T+TB3T,1 case of TB3T+TB2T+TB1T,1 case of MT in 34 cases of thymoma.(2)β5t was expressed in neoplastic epithelial cells cytoplasm and dotted of TAT (4/4) and in neoplastic epithelial cells cytoplasm and nulcear in TBT (20/20). Among the subtypes B thymoma, degree of expression was+++in TB1T (10/10),++in TB2T (4/6),+TB2T (2/6),and i-n TB3T++( 1/1),+TB3T (1/1).Degree of expression declined from TB1T to TB2T, TB3T (P < 0.001),there was no difference between TB2T and TB3T(P=0.5357).In TABT showed two patterns as in above. It was negative in MT. (2) Positive rate of p63 in thymoma was 60%～100%. p63was expressed in large sheet of TAT, scattered distribution in TB1T,cluster or small sheet in TB2T and large sheet in TB3T.It was positi-ve in epithelioid cells of MT and negative in spindle cells. (3) The experssion of CD20 was focal positive in TAT and TABT (4/4,8/9) and was negative in TBT and MT.Conclusion:The different expressions of β5t in subtype thymoma contribute to the diagnosis of thymoma. The combined expression of β5t, p63 and CD20 co-uld be better to classificate thymoma and β5t compared with p63 could be bett-er differentiateTBT. The decline of expression intensity of β5t from TB1T to T B2T,TB3T suggested the postulated cell of origin in B2 and B3 is a thymicepi- thelial cell capable of differentiating towards a less differentiatedcorticaltype epi-thelial cell than in TB1T. At the same time, positive for β5t and CD20 was be neficial to the differential diagnosis between TAT from MT.