What is the most common testicular tumor in children?

The most common testicular tumor in children is indeed the yolk sac tumor, also known as endodermal sinus tumor. This tumor arises from germ cell components and is most frequently seen in children under the age of 3. Yolk sac tumors typically present as a painless testicular mass and can be associated with elevated levels of alpha-fetoprotein (AFP), which serves as a useful tumor marker for diagnosis and monitoring treatment response.

The pathogenesis of yolk sac tumors is linked to the aberrant differentiation of germ cells during development. In the pediatric population, these tumors are primarily found in the context of germ cell tumors, distinguishing them from the patterns seen in adults, where testicular tumors often consist of seminomas and non-seminomatous germ cell tumors.

On the other hand, embryonal carcinoma, while it is a non-seminomatous germ cell tumor and may occur in children, is less common overall compared to yolk sac tumors. Sertoli cell tumors are also rare in children and typically present as hormone-secreting tumors, which further distinguishes them from the most common types found in this age group. Seminoma is primarily seen in older adolescents and adults and is not the predominant form of testicular cancer in