Which of the following is not true for endodermal sinus tumor:

he endodermal sinus tumor or yolk sac tumor mostly observed between 15-20 /yrs of age. It os the second most common malignant germ cell tumor of the ovary (most common gm cell malignancy is dysgerminomA.. These are unilateral. The characteristic histological feature is presence of cystic spaces; a tuft of vascular tissur often seen. This s called as schiller -Duval body The tumor is highly malignant and spreads to the adjacent structures rapidly . Surgical staging and unilateral sapingo- oopherectimy is generally the treatment of choice.