[Expression of CD117 in human testicular germ cell tumors and its diagnostic value for seminoma and nonseminoma].

Objective: To evaluate the expression of CD117 in human testicular germ cell tumors and its value in the differential diagnosis of seminoma and nonseminoma.

Methods: Seventy-four human testicular germ cell tumor specimens were studied by ABC kit immunohistochemical staining detection using CD117 monoclonal antibodies. The immunoreaction scores (IRS) of all the specimens were calculated and analysed for their clinical significance.

Results: Among the 74 germ cell tumors, 31 out of 32 (9 6.9%) seminomas showed positive staining of the CD117 mostly on the cell membrane. Four of 31 (12.9%) nonseminomas displayed a weak positive staining of CD117 only in the cytoplasm of a few cells. In 10 of 11 mixed germ cell tumors, a relatively weak expression of CD117 was shown only in the seminoma component. The CD117 expression was diagnostically decreased from seminoma to mixed seminoma and to nonseminoma successively, with IRS of 6.82 +/- 2.76, 1.25 +/- 0.42 and 0.60 +/- 0.16, respectively. There was a significant difference in the CD117 expression between seminoma and nonseminoma (P < 0.05). CD 117 proteins were positively expressed in all the 20 specimens of the normal testis.

Conclusion: The detection of CD117 by immunohistochemical staining using CD117 monoclonal antibodies is a newly developed useful method for differentiating seminoma and nonseminoma.