Monoclonal antibody 43-9F as a sensitive immunohistochemical marker of carcinoma in situ of human testis.

Invasive germ cell cancer can be prevented if the neoplasia is diagnosed at the stage of carcinoma in situ (CIS). In routine histologic examination CIS may be overlooked, particularly in prepubertal individuals. The detection of this early malignancy may be greatly facilitated by use of immunohistochemical staining. The authors investigated the sensitivity of an immunohistochemical staining procedure with monoclonal antibody 43-9F in detection of CIS. Testicular specimens from 19 adult and two prepubertal individuals with CIS were tested. Positive staining reaction on the surface of malignant germ cells was encountered in all 21 specimens with CIS. The epithelial cells of the excretory ducts between testis and epididymis, including rete testis and canaliculi efferentes, reacted also positively with 43-9F. No staining was observed in nonmalignant testicular cells including Sertoli cells or Leydig cells in any of these samples or in testicular biopsy specimens from 27 adult and 11 prepubertal subjects without evidence of testicular neoplasia. Monoclonal antibody 43-9F was also found to react with cells of all four tested invasive testicular germ cell tumors. Thus, the monoclonal antibody 43-9F is a sensitive immunohistochemical marker of CIS germ cells and may also be of potential value in detection of invasive testicular cancer.