Practices recommendations in the applications of immunohistochemistry and molecular genetics in testicular tumors. Review article.

The great majority of testicular tumors can be diagnosed on the basis of morphology, while immunohistochemistry and molecular genetics assist in only a small proportion of cases. Similar to other areas of pathology, ancillary diagnostic methods have to be used responsibly and assessed in correlation with morphological, serological and clinical findings. Prior to their effective use, a limited differential diagnosis based on morphology is required.The significance of germ cell tumors is underscored by the fact that they represent the most frequent solid neoplasms occurring in men between 20-30 years and if diagnosed correctly and in early stage, they have excellent prognosis. From the molecular genetic standpoint, germ cell tumors stand apart from the current trend of tumor stratification based on molecular profiles. It is mainly due to the low mutational load, since the main genetic abnormality are chromosomal aneuploidies. Given the frequency of germ cell tumors among testicular neoplasms and since morphology is usually diagnostically most valuable, this review article is focused mainly on germ cell tumors, emphasizing the morphological features. Sertoli cell tumor, NOS is the only sex-cord stromal tumor included in this review as its diagnosis can be challenging. For practical purposes, this reviewis focused on differential diagnosis, including only entities where misdiagnosis would have impact on clinical outcome.