CD117 Expression In Human Testicular Germ Cell Tumors

Objective (1) To observe the differences of CD117 protein expression among seminoma, nonseminoma and mixed germ cell tumor.(2) To evaluate the diagnostic value of CD117 in differentiating diagnosis for seminoma and nonseminoma.Methods: 74 human testicular germ cell tumors and 20 normal testicular tissue specimens were studied with ABC kit immunohistochemical staining detection using CD117-monoclonal antibody. The immunoreactive intensity and density of each case were measured. The immunoreactive score(IRS) in all specimens were calculated and analysed for their clinical significance. Results: All the 20 specimens of normal testis were positive for CD117 protein expression, while positive expression of CD117 was demonstrated in 45/74 of testicular germ cell tumors with the positive rate of 60.8%. Among the 74 germ cell tumors, thirty-one out of 32 (96.9%) seminomas showed positive staining of the CD117on the cell membrane in majority of cells. Four out of 31(12.9%) nonseminomas displayed a weak positive staining of CD117 only in the cytoplasm in a few cells. In the ten out of 11 mixed germ cell tumors, the relative weak expression of CD117 was showed only in theseminoma component. The CD117 expression was diagnostically decreased from seminoma to mixed seminoma and to nonseminoma successively, IRS was 6.82 + 2.76,1.25 + 0.42 and 0.6 + 0.16, respectively. There was a significant difference of the CD117 expression between seminoma and nonseminoma (PO.05) . Both the positive expression rate and the IRS of CD117 were significantly decreased in higher grade tumors than those in lower grade tumors (PO.005) . But there was not relationship between the expression of CD117 and either clinical stage or lymph node metastasis of the tumors (PO.005) .Conclusions: (1) CD117 expression is decreased in testicular germ cell tumors than that in normal testicular tissue. (2) CD117 expression is significantly varied in different kind of testicular germ cell tumors. It expresses with a higher positive rate and most in the cell membrane in seminoma, while there is a lower positive rate and only weakly stained in cytoplasm in nonseminoma. CD117 expression is only displayed in the seminoma component in the mixed germ cell tumors. (3) The detection of CD117 by immunohistochemical staining using CD117 monoclonal antibody is a newly developed useful method for differentiating seminoma and nonseminoma. (4)Abnormality of SCF / CD117 signal transduction system might play a promotive role in the genesis, development and differentiation of testicular germ cell tumors.