Login to Access Video or Poster Abstract: MP80-18
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Introduction

Embyrologically, gonads are derived from mesonephrons while kidneys are derived from metanephrons. Our previous study demonstrated a positive association between kidney injury molecule-1 (KIM-1) staining and renal cell (papillary/clear cell type), and ovarian carcinoma (clear cell). The preliminary data also revealed positive KIM-1 staining in the tubules of mesonephrons, raising the possibility of KIM-1 expression in various testicular tumors. This study was to investigate whether KIM-1 and CD133 (a progenitor cell marker known to be positive in some renal cell carcinoma) expressions can help predict or differentiate various germ cell neoplasms of testis.

Methods

A total of 29 cases of seminoma and 31 cases of mixed germ cell neoplasms were identified. Tumors were sectioned and immunohistochemically stained for KIM-1 (AKG7 monoclonal KIM-1 antibody from JV Bonventre, BWH, Boston, at dilution 1:10) and CD133 (AC133 monoclonal antibody, Miltenyi Biotec, at 1:100 dilution). The membranous staining of each marker was graded 0 to 3+ and the percent of expressive distribution was recorded.

Results

KIM-1 was found to stain 77.4% (24/31, intensity at 1 to 3+, and distribution ranging from 1 % to 90 %) of mixed germ cell neoplasms (predominantly embryonal and yolk sac components), whereas there was no KIM-1 expression in benign seminiferous tubules, mature teratoma, classic seminoma and Leydig cell tumor. Scattered and weak CD133 staining was seen in seminoma and mixed germ cell tumors (10% and 16% respectively) and absent in benign tissue, mature teratoma and Leydig cell tumor.

Conclusions

Our data suggest that KIM-1 expression can be used to differentiate mixed germ cell neoplasms from pure seminomas (negative for KIM-1 staining). CD133 appears to be not as useful in differentiating various testicular tumors.

Funding

None