This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, Subject name: Pathology
Metastasis is least common with 
Select and explain. 
A. Embryonal cell carcinoma, B. Endodermal sinus tumor, C. Taeratocarcinoma, D. Spermatocytic Seminoma
B: Endodermal sinus tumor
Answer: B: Endodermal sinus tumor 
Explanation: Also known as endodermal sinus tumor, yolk sac tumor is of interest because it is the most common testicular tumor in infants and children up to 3 years of age. In this age group it has a very good prognosis. In adults the pure form of this tumor is rare; instead, yolk sac elements frequently occur in combination with embryonal carcinoma.