False-negative biopsy for testicular intraepithelial neoplasia and high-risk features for testicular cancer.

The purpose of this report is to emphasize the possibility of false-negative biopsies for testicular intraepithelial neoplasia (TIN) in men with high-risk features of testicular cancer and to review the relevant literature. At the Norwegian Radium Hospital patients in this category are offered the chance to undergo a testicular biopsy. A patient is described who had a normal testicular biopsy a decade before presenting with an invasive testicular cancer. Furthermore, this patient is the first case reported with a false-negative biopsy for TIN and a family history of testicular cancer. The evaluation of the biopsies included immunohistochemical staining for c-kit and PIAP (placental-like alkaline phosphatase) in order to diagnose early TIN. Though multifocal or diffuse extension seems to be the most frequent pattern of distribution of TIN, the presented case and another 14 cases from the literature review indicate that the focality of TIN may be a reason for a TIN-negative biopsy.