Section Editor: Dharam M. Ramnani, MD

Virginia Urology, Richmond, VA, USA

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Yolk sac tumor (YST; previously known as endodermal sinus tumor) is the most common testicular germ cell tumor (GCT) in childhood accounting for almost 75% of prepubertal testicular GCT. Post-pubertal YST is usually seen as a component of a mixed GCT (about 44% of cases). Pure YST in exceedingly rare in post-pubertal patients and accounts for only 0.6% of testicular GCT in this age group.

Clinical Features: The median age at presentation in prepubertal patients is 16-19 months. Post-pubertal patients are usually between 15-40 yrs. of age. Rare cases have been reported in the elderly. The presentation is usually in the form of a painless testicular mass. Serum alpha fetoprotein (AFP) levels are elevated in more than 90% of cases. It should be remembered that the reference range for serum AFP is physiologically higher in infants than in older patients.

Prepubertal yolk sac tumor is not hormonally active. There is no association with cryptorchidism or gonadal dysgenesis. Between 10%-20% of children with YST present with metastases, usually to lungs followed by retroperitoneal lymph nodes, liver, and bones. When metastases develop later, they usually appear within 14 months of diagnosis.

Image copyright: pathorama.ch

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