Double immunolabeling by the RBM and the PLAP markers for identifying intratubular (in situ) germ cell neoplasia of the testis.

Identification of intratubular germ cell neoplasia (carcinoma in situ, CIS) of the testis is a diagnostic challenge, and markers are sorely needed to assist in accurately identifying the lesion. RNA-binding motif (RBM) protein, encoded by the Y chromosome, is expressed exclusively and consistently in differentiated male germ cells, while it is absent in neoplastic germ cells. Another immunohistochemical marker, placental alkaline phosphatase (PLAP), is commonly used for the detection of undifferentiated germ cells. The current study demonstrates that simultaneous use of the immunohistochemical markers, RBM and PLAP, by double immunolabeling enhances the accuracy of diagnosing CIS, a preinvasive testicular neoplasm.