Sex cord-stromal tumors account for approximately 2-5% of testicular neoplasms in adults but make up almost 25% of cases in children. The category includes pure sex cord and pure stromal tumors as well as mixed tumors with both components in varying proportions and unclassified tumors. The clinical behavior is benign in 90-95% of cases. Most tumors are non-functioning. A small proportion of cases are associated with feminizing symptoms or isosexual pseudoprecocity. Tumors that pursue a malignant course (5-10% of cases) generally have atypical histologic features. References:Cheng, L., MacLennan G. T., & Bostwick, D. G. (2020). Urologic Surgical Pathology - 4th Edition. Elsevier. Moch, H. et al (2016). WHO Classification of Tumours of the Urinary System and Male Genital Organs. 4th Edition. Wein, A. J. et al (2012). Campbell-Walsh Urology - 10th Edition. Philadelphia, PA. Elsevier Saunders.