Sertoli cell tumor in familial adenomatous polyposis: a case report.

Familial adenomatous polyposis is known to progress into colorectal cancer, and extra-intestinal malignancies have also been reported. However, testicular sex cord stromal tumors are very rarely noted in association. In this study, we report the case of a 50-year-old man with genetically confirmed FAP and adenocarcinoma of the colon who was incidentally found to have a testicular lesion. Radial orchiectomy was performed, and histopathologic examination confirmed a Sertoli cell tumor without high-risk features. This tumor was found to have diffuse expression of nuclear beta-catenin, a marker for Wnt pathway activation, suggesting an abnormal CTNNB1 or APC variant. This suggests a possible link between germline APC mutations and Sertoli cell tumor development.