Purpose: Testicular intraepithelial neoplasia (TIN), also called intratubular germ cell neoplasia, is thought to be the precursor of testicular germ cell tumors (GCTs). Evidence for this theory stems from clinicopathological studies because to our knowledge experimental models are lacking. While GCT clinical risk groups have been studied extensively for TIN, only 1 small study to date has assessed the presence of TIN in the general population. In the current study we analyzed the prevalence of TIN in a large group of healthy men.
Materials and methods: Bilateral testicular specimens were obtained from 1,388 presumably healthy men who died unexpectedly and underwent autopsy at forensic institutes in Germany. Median age in this patient sample was 33 years. Specimens were fixed in Stieve's solution and all specimens were examined immunohistologically with placental alkaline phosphatase staining.
Results: TIN was found in 6 cases (0.43%, 95% CI 0.16 to 0.94). Two cases also showed microinvasive seminoma. TIN was bilateral in 1 case. The right testicle was afflicted in 4 cases and the left was affected in 1. Median age of the individuals with TIN was 33 years.
Conclusions: As found in the current study, the prevalence of TIN is consistent with the lifetime risk of GCT in Germany. Data in the current study are in accordance with those in a previous study from Denmark. In all these data represent fundamental support of the role of TIN as the precursor of GCT.